HIV Risk Calculator & Complete Exposure Guide (2026)
🕓 Last updated: 14 January 2026
How HIV risk is calculated, step by step, using published evidence and clear probability.
The most sophisticated AI HIV risk calculator on the web.
HIVRiskReport is a private, educational tool that estimates the statistical risk of HIV transmission from a single sexual encounter. It uses published epidemiological data from sources such as the CDC and peer-reviewed medical studies to translate multiple risk factors into one clear probability, shown as both a percentage and a “1 in X” figure. This report does not diagnose HIV or predict individual outcomes, but it helps replace vague anxiety with realistic context and guidance on appropriate next steps, including testing when needed.
CALCULATE YOUR HIV RISK USING OUR
PROPRIETARY, PRIVATE
AI ASSESSMENT TOOL.
Built to give peace of mind and replace panic with probability
Guide Contents
Jump straight to the part of the HIV exposure guide that matches what you need most right now.
- 1. What determines HIV risk?
- 2. What goes into your personalized calculation
- 3. Most common scenarios explained (these will help)
- 4. HIV testing timeline
- 5. PEP after exposure
- 6. Why this risk engine is state of the art
- 7. Why you can trust this tool
- 8. Get your personalized HIV risk report
- 9. More HIV risk and testing resources
- 10. Important disclaimer
Your clear, structured path through HIV risk
This guide was created to help you understand HIV transmission risk using real data, clear logic, and step-by-step explanations. No guesswork, no conflicting articles, and no panic loops, just a grounded framework you can follow from start to finish.
What Determines HIV Risk?
HIV risk can be estimated by analysing a number of different variables. Although testing is the only way to know your true status, knowing the risk transmission probability of a single encounter can help bring peace of mind and eliminate anxiety. It comes down to two questions: could your partner have HIV, and if so, how efficient was the exposure? Everything else is a modifier that pushes the estimate up or down. If you want the number for your exact encounter, you will need a personalized calculation.
What Determines Risk:
How common HIV is in your partner’s context, plus how likely treatment has reduced infectiousness.
The type of sex and your role, because different tissues transmit differently.
Condoms, PrEP, ejaculation location, and signs of irritation or other infections.
1) Partner HIV status and prevalence
The starting point is simply: what is the chance your partner has HIV in the first place? That varies by setting and network, so we estimate it from epidemiological data that matches what you report.
- Location: country and sometimes region-level differences.
- Demographics: gender and the relevant sexual network.
- Context: risk factors you report (or do not report).
- Treatment reality: when status is unknown, we account for how often people are diagnosed, on ART, and virally suppressed.
2) Type of sex and role
Not all exposure routes have the same efficiency. In general, mucosal tissue that is thinner and more prone to micro-tears carries higher per act risk, especially without barriers.
- Receptive anal: typically the highest per act risk.
- Insertive anal: lower than receptive anal, but not “nothing”.
- Vaginal sex: generally lower than anal, with differences by role.
- Oral: usually low to negligible in most circumstances.
- Non-penetrative contact: effectively zero for HIV in normal scenarios.
3) Condoms and what happened to them
Condoms are one of the most reliable “downward multipliers” when used correctly and they stay intact. The detail that matters is not intention, it is execution.
- If it stayed on and did not break or slip, the estimate drops substantially.
- If it broke, slipped off, or was not used, the calculation reflects unprotected exposure.
- If you are unsure, your report shows how uncertainty affects the result.
4) Viral load, ART, and the U equals U effect
Viral load is the biggest swing factor once someone actually has HIV. When a person is on ART and maintains an undetectable viral load, sexual transmission does not occur. That is the science behind U equals U.
- Known HIV-positive partner on effective ART: the estimate collapses towards zero.
- Unknown status: we use country-level treatment and suppression patterns to avoid unrealistic assumptions.
5) Wounds, inflammation, and other infections
Cuts, sores, significant irritation, or an active STI can increase susceptibility because the barrier is compromised. This matters most when there is unprotected anal or vaginal exposure.
- We ask simple questions so you can include this without over-explaining.
- If you prefer not to share, the report stays conservative and transparent about assumptions.
6) Why a personalized report is different
Most articles stop at generalities. Your report shows the actual numbers, the assumptions, and how each input moves the estimate. You should be able to look at the result and understand why it is that number.
- A clear probability in percent and “1 in X”.
- A step-by-step explanation, not a generic reassurance.
- Practical next steps that fit the risk tier.
Why general articles can’t answer your question
Most HIV websites are written to be broadly true, but not personally accurate. They have to cover every country, every partner profile, and every type of exposure, so the data stays deliberately general. Your question is more specific: what does this mean for my EXACT encounter? The answer depends on concrete inputs such as local prevalence, your role, what actually happened with protection, real-world treatment and viral suppression, and whether there were cuts or irritation. When any of these details are guessed or misunderstood, people often end up in the worst of both worlds: unnecessary panic, or false reassurance. A personalized calculation replaces guesswork with a transparent, step-by-step estimate, giving you a clear probability, the assumptions behind it, and next steps matched to your risk tier.
What Goes Into Your Personalized Calculation
Generic hiv risk calculators cannot tell you what your specific encounter means, because they ignore the exact inputs that change the maths. A personalized report takes your answers, maps them to evidence-based baseline rates, then applies only the modifiers that your scenario actually earns.
| Variable we use | Why it matters in the calculation |
|---|---|
| Date of encounter | Anchors all timing guidance, including when testing becomes reliable and whether PEP could still be time-relevant. It also keeps the assessment tied to one specific event, rather than a vague timeframe. |
| Country of encounter | Determines the baseline prevalence estimates and treatment cascade assumptions we use in the model. HIV rates, diagnosis coverage, and viral suppression vary meaningfully by country, which can move the final estimate up or down. |
| Your gender | Helps select the correct baseline prevalence context and ensures the per-act transmission estimates match the anatomy and exposure route relevant to you. |
| Partner’s gender | Used alongside location to choose the correct partner prevalence estimate and to match the correct per-act transmission pathway (for example, vaginal versus anal exposures). |
| Partner known HIV-positive | If the partner is confirmed positive, the model shifts reminder focus to treatment and viral load. If status is unknown, the report estimates the likelihood they have HIV based on epidemiological data. |
| Type of sexual activity | Sets the baseline per-act transmission probability. Vaginal, anal, and oral exposures have very different statistical risk profiles, so this is one of the biggest “starting point” inputs. |
| Your role (insertive or receptive) | Selects the correct per-act risk within the sex type. Receptive and insertive roles are not interchangeable in the maths, especially for anal and vaginal sex. |
| Condom use | Applies a major downward multiplier when a condom was used properly and stayed intact. If no condom was used, the model treats the exposure as unprotected, which typically increases risk materially for anal or vaginal sex. |
| Partner injection drug use or other major risk factors | Adjusts the estimated likelihood that the partner has HIV when additional high-exposure risk factors are present. If absent or unknown, the estimate stays anchored to baseline prevalence for the selected setting. |
| Sex worker encounter | Changes the prior probability of exposure because certain occupational contexts have statistically different prevalence patterns. The model treats this as a partner-likelihood modifier, not a moral judgement. |
| Partner had multiple partners recently | Used as a context signal that can increase exposure probability in some scenarios. When unknown, the report stays conservative and explains how uncertainty affects the estimate. |
| Ejaculation inside the body | Influences exposure intensity because semen can carry HIV when viral load is not suppressed. This is treated as an upward modifier in unprotected vaginal or anal sex, and a minimal factor in most oral-only scenarios. |
| Partner on HIV treatment (ART) | Treatment status is one of the biggest swing factors if the partner has HIV. Effective ART that results in viral suppression can reduce transmission risk to effectively zero. If treatment is unknown, the report uses country-level coverage and suppression patterns rather than assuming worst case. |
| You take PrEP | Applies a strong downward modifier because PrEP meaningfully reduces acquisition risk when taken correctly. The report explains how adherence assumptions affect how much protection is credited. |
| Wounds or inflammation | Cuts, sores, irritation, or active STIs can increase susceptibility by compromising tissue barriers, especially in unprotected anal or vaginal sex. This is applied as a conditional upward modifier when relevant. |
| Circumcision status | Considered only when it is biologically relevant to the exposure route (typically insertive vaginal sex). If it does not apply, the model keeps it neutral and explains why it was not used as a multiplier. |
| [NEW] personalized content analysis | A plain-language layer that converts the maths into an understandable explanation, flags the specific variables that drove your result, and points you towards the next best action for your risk tier. |
This is why two people can have the “same” type of sex but end up with different real-world risk. The personalized report does not rely on generic labels. It shows the inputs, the assumptions, and the step-by-step logic behind the final number.
Most Common Scenarios Explained
A sore throat can be a source of major anxiety. This guide breaks down the key differences between a sore throat from an acute HIV infection and one from common allergies.
Read More →Feeling worried about prevention? This guide explains the difference between PrEP (for before exposure) and PEP (for after) to help you understand your choices clearly.
Read More →Anal sex can trigger major HIV anxiety, but the real risk depends on role, viral load, and prevention. This scientific guide breaks down receptive vs insertive risk, how condoms and PrEP change the odds, what U=U means, and when to consider PEP and testing.
Read More →Wondering what undetectable actually means for HIV transmission? This article explains viral load, U=U, and how effective treatment can reduce sexual transmission risk to essentially zero.
Read More →Swollen glands can be a symptom of many things, including HIV. This article gives you a calm, factual look at the connection between HIV and lymph nodes, and when to get tested.
Read More →Worried about HIV in the air, on surfaces, or in dried fluids? This calm, evidence-based guide explains what actually happens to HIV outside the body, and why everyday contact is not a realistic transmission route.
Read More →What is the real connection between sex work and HIV risk? This article looks past the stigma and explains the facts and factors that are most important to know.
Read More →It is easy to worry about symptoms. This guide helps you separate unreliable signs from real information, so you can focus on testing instead of fear.
Read More →Studies show that HIV transmission from female to male is less common. This article explains the simple biological reasons why this is the case.
Read More →Curious whether circumcision makes sex safer? This article explains how circumcision changes HIV risk for insertive partners and why viral load, condoms and PrEP still matter more.
Read More →Panicking over a rash after sex? This scientific guide explains what an acute HIV (seroconversion) rash can look like, how it differs from hives or heat rash, and why timing plus proper testing beats symptom-scanning.
Read More →Feeling stuck in a cycle you can’t control? This evidence-based guide breaks down compulsive sexual behaviour and problematic porn use, explains the habit loop and drivers, and gives a practical recovery plan you can start today.
Read More →Pre-cum is not semen, but it can carry HIV under specific biological conditions. This article explains how viral load, urethral shedding, and mucosal tissue determine real-world risk, why U=U changes everything, and what withdrawal stats imply.
Read More →Feeling anxious after a possible exposure is normal. A risk calculator is a tool to help you look past fear and see your situation based on facts and science.
Read More →This is a very common question. This article breaks down the real risk of HIV from oral sex, separating myths from medical facts to give you clear information.
Read More →Timing is key for an accurate test result. This guide explains the window periods for both lab blood tests and at home oral tests so you can choose the right one.
Read More →HIV Testing Timeline Calculator
Knowing when you can test and trust the result is often just as important as knowing the probability itself. This section gives general windows, however your personalized report uses your actual encounter date to generate exact earliest and conclusive test dates, based on the best available evidence from organisations such as CDC.
OraQuick and similar oral swab tests
- Begin to detect many infections around three weeks after exposure.
- Considered conclusive at twelve weeks for most guidelines.
Fourth generation blood tests
- Detect many infections around fourteen days after exposure.
- Usually considered conclusive at forty five days for a single high risk event.
PCR or RNA tests
These tests detect viral genetic material directly and can identify infection earlier than antibody or antigen tests. They are not routinely recommended for standard screening, but they may be used in specific high risk or clinical situations.
Your HIVRISKREPORT output calculates personalized earliest and conclusive testing dates based on the exact date of your encounter and the type of test you plan to use.
PEP: Emergency HIV Prevention After Exposure
Post Exposure Prophylaxis, often shortened to PEP, is a course of HIV medication that can reduce the chance of infection after a high risk exposure. It is time sensitive and must be started quickly.
- PEP must be started within seventy two hours of the exposure.
- It is most effective when started within the first twenty four hours.
- It is usually recommended for specific higher risk situations such as unprotected receptive anal sex with a partner known to be HIV positive or in a high risk group.
If your encounter was more than seventy two hours ago, PEP is no longer an option. In that case the focus shifts to accurate testing at the right times, which your personalized report can help you plan.
Always speak to a local sexual health clinic or emergency department if you think you may need PEP. This site does not replace medical advice.
Why This Risk Engine Is State of the Art
Bayesian probabilistic model
The HIVRISKREPORT engine is a structured probabilistic inference model, not a heuristic “risk score”. It operates as a Bayesian cascade: it starts with an epidemiology-informed prior for partner HIV positivity (conditioned on geography, partner demographics, and relevant sub-population prevalence), then updates via an exposure-specific likelihood term drawn from per-act transmission literature (stratified by act type and insertive versus receptive role), then applies only scenario-valid multiplicative modifiers as conditional factors (for example condom effectiveness, ART-driven viral suppression and U=U, PrEP protection, and tissue-disruption or inflammation effects). In statistical terms, the report estimates an individualised posterior transmission probability by combining base rates with conditional probabilities, explicitly separating uncertainty in the partner-status prior from the mechanistic transmission likelihood, then propagating uncertainty through a transparent, auditable computation rather than collapsing inputs into a single opaque label.
Why You Can Trust This Tool
HIVRISKREPORT was created because anxiety after a sexual encounter can become overwhelming. People search the internet, see worst case stories, and struggle to think clearly. Putting numbers on the situation does not erase risk, but it can help bring fear down to something more manageable.
The model behind the report is based on published research rather than guesswork. Key sources include:
- Per act HIV transmission risk meta analyses.
- Country level prevalence and treatment coverage data from organisations such as CDC and UNAIDS.
- Studies on condom effectiveness and viral suppression.
On top of that, the site has been reviewed by an independent trust checker and currently holds an external trust rating of 83/100. You can view the external trust report if you want to verify this yourself before using the calculator or paying for a report.
You remain anonymous when you use the tool. The goal is to provide clarity and structure to a situation that often feels chaotic and frightening.
“A great counterweight to all the panic posts on Reddit. It greatly reduced my anxiety related to a recent “incident” and I am forever grateful that you took the time and effort in creating this service.”
When your brain will not switch off
If you keep replaying the encounter in your head and swinging between “I am fine” and “what if I ruined my life”, this guide and the calculator give you one clear framework instead of endless mental loops.
When Google made it worse
You might have opened ten tabs, seen horror stories and vague odds, and walked away more confused. Here you get a single, calm explanation built from real data, all in one place.
When you need a plan not more panic
Instead of guessing or waiting in fear, you leave with a clear understanding of what drives risk, when to test, and how a personalized report can turn “what if” into “here is what I will do now”.
Get Your Personalized HIV Risk Report
This guide explains the general rules of HIV transmission. Your personalized report takes the next step and applies those rules to your exact encounter, turning vague fear into a single, clear number you can understand and act on.
What your report includes
personalized Risk Analysis
- A fully personalized, 6-page HIV risk assessment based on your partner, country, type of sex, role, condom use, ART or PrEP, wounds, ejaculation, duration, and more.
- Partner HIV probability modelling using country and group-specific data rather than generic averages.
- All upward and downward modifiers clearly listed, including condoms, ART, PrEP, circumcision, wounds, and type of sex.
Clear, Step-by-Step Explanation
- A plain-language walkthrough showing exactly how each part of your encounter affects risk.
- Your final risk shown four ways: percentage, decimal, fraction, and a simple “1 in X” format.
- A “what helped and what hurt” summary highlighting which factors lowered risk and which increased it.
Testing & Next Steps
- A personalized testing timeline with earliest and conclusive dates for RNA tests, 4th generation blood tests, and at-home oral tests.
- A clear next-step plan so you know exactly what to do after reading your report.
- Risk-tier specific FAQ answers tailored to your actual probability, not generic advice.
Perspective & Reassurance
- Real-world comparisons that place your risk alongside everyday events and other common STIs.
- A brief alternative scenario showing how risk would change if one key detail were different.
- Emotional reassurance written for people experiencing panic or health anxiety.
Your report is generated as a confidential, password-protected PDF that you can save to your device and read in private. No account, no sign-up, and no sharing of your name.
More HIV Risk and Testing Resources
Version Updates
Our risk engine is constantly being refined based on the latest data:
- Sex Worker Risk Model Update: Refined how sex work is incorporated into partner prevalence estimates, using region-specific multipliers that are more conservative and more realistic.
- Improved Key Population Handling: Prevents over-inflation when a key population baseline is already being used (for example MSM), reducing double counting while still accounting for increased exposure risk.
- Stability and Trust: Added caps and dampening logic to keep outputs within credible real-world ranges, improving consistency across regions.
- Report Design Re-designed to entire report for a more modern look and feel
- Geo-Specific Accuracy: The risk engine's analysis is now even more precise by explaining how country-specific data (HIV prevalence and healthcare system effectiveness) is used to calibrate the final probability.
- RNA Testing: Report now includes suggested dates for RNA testing based on the encounter date.
- Transparency Update: The FAQ section now includes a full breakdown of the HIV Treatment Cascade equation, showing exactly how we calculate risk for partners with an unknown ART status.
- Empowerment Update: Reports now conclude with a "Path Forward" section, reframing the experience from anxiety to agency and highlighting the knowledge the user has gained.
- Major Update I: Refined the sex worker risk multiplier with region-aware logic based on UNAIDS prevalence data.
- Major Update II: Integrated PrEP (Pre-Exposure Prophylaxis) logic into the risk calculation.
- The model now accounts for user adherence with specific pathways for perfect daily use, on-demand dosing (2-1-1), missed doses, and recent initiation.
- Each adherence level is mapped to a clinically-backed risk reduction multiplier, for example up to 99% for perfect use.
- Patched linguistic ambiguity in the risk modifier output.
- Enhanced tissue integrity modelling for transmission probability.
- Corrected HIV prevalence data streams for MSM versus general population.
- Implemented an ART logic override: the template now automatically uses the more realistic "Don't Know" ART calculation if the partner's overall HIV status is "Don't Know", even if "No" was selected for the ART question.
- Updated circumcision logic: the upward risk multiplier for being uncircumcised now only applies if a condom was not used.
- The protective benefit of "no ejaculation" is now correctly applied only to receptive partners. Previously this required a manual QA change.
- Report now includes a “Comparison to Other STIs” section showing relative likelihoods versus HIV.
- Added test timing calculator based on the user’s exposure date.
- Shows personalized lab and oral test dates to avoid false negatives.
- ART coverage logic improved, now factoring in three country-level statistics (diagnosis rate, treatment access, and viral suppression) to give a more realistic picture of how many people are actually suppressed. This helps account for undiagnosed cases and better reflects real-world transmission odds.
- Sex worker risk logic revised, adjusted to be more conservative while still accounting for higher exposure rates due to occupational partner turnover.
- Multiple partners logic refined, risk estimates now better reflect the increased exposure likelihood when a partner has had two or more partners in the past six months.
- ART coverage now splits by population: MSM versus general public.
- Improves accuracy by reflecting real-world disparities in ART access for MSM.
- Expanded risk pathway logic to account for instances where the user is not circumcised.
- Wound and inflammation risk now included, increasing transmission estimates if the user had open cuts, sores, or irritation during sex (only applied when no condom was used).
- Step Two now clearly explains how wound-based risk affects overall probability, using plain language.
- The full breakdown of probability logic now includes a clearer explanation of how the partner’s HIV estimate and act-specific transmission risk combine to calculate final odds.
- PEP guidance now adapts to risk tier, clarifying when it is typically not recommended but still available for high-anxiety or anal sex cases.
- New “What If It Was Anal?” FAQ added for users who select “multiple sex types” without specifying the act.
- “What We Recommend” section rewritten for sharper tone, emotional clarity, and faster readability.
- Real-world ART logic now applies regional treatment coverage rates when ART status is unknown.
- Expanded risk pathway logic to include role-specific (insertive versus receptive) modifiers.
- MSM-specific prevalence now replaces general population prevalence for male-male encounters.
- Introduced emotional reinforcement and alternate scenarios to reduce panic.
- Added personalized risk recommendations based on calculated probability.
- Cleaned up visual flow for mobile-first readability.
- Transitioned to per-act risk modelling using fraction and percentage logic.
- Integrated global gender-stratified HIV prevalence estimates.
- Upgraded condom effectiveness to reflect real-world meta-analytic data.
- Introduced transparent breakdown of all conditional inputs in Step Three.
Disclaimer
HIVRISKREPORT is an informational and educational tool. It does not replace medical advice, diagnosis, or treatment from a qualified healthcare professional. If you think you may have been exposed to HIV, or if you feel unwell, contact a sexual health clinic, your doctor, or an emergency service in your area.