Use this calculator to estimate your chance of pregnancy from an encounter where a condom was used. Choose whether it was perfect or typical use, then (optionally) add a second method. Your result is per-act, based on peer-reviewed effectiveness data and our modelling. It’s not medical advice—just a clear way to put numbers to a stressful question.
* Calendar dates cannot confirm ovulation or identify a safe day. This is an approximate per-act estimate, not a measured personal chance.
How to read your result
- Per-act chance: The percentage shown is for that single encounter, not a whole year.
- Perfect vs typical: Typical use includes late application, slippage, or breakage. Perfect means on from start to finish, with space at the tip and no tears.
- Second method: Adding a method (e.g., pill, withdrawal method) lowers risk further. Use the “Other contraceptives (optional)” drawer to combine.
Want to see the math behind our estimates? Read how our calculators work.
How to lower your risk next time
- Use the right size; check the expiry date and package integrity.
- Pinch the tip to leave space, unroll to the base, and add lubricant if needed (water- or silicone-based with latex).
- Hold the rim during withdrawal and change condoms between acts.
- Consider “stacking” methods (e.g., condoms + pill) for extra protection.
If the condom broke, slipped, or wasn’t on the whole time
Emergency contraception (EC) works best ASAP after intercourse. Compare options and timing with our Emergency Contraceptive Pill Effectiveness Calculator.
When to take a pregnancy test
Most people get a reliable result from the first missed period. To see how accuracy changes by day, use the Pregnancy Test Accuracy Calculator.
Methodology
Cycle day 1 is the first day of your period. Calendar timing follows the all-women estimates for days 1-40 in Li, Wilcox and Dunson (2015), Table 3. These estimates allow for variation in ovulation timing rather than treating a predicted ovulation date as certain.
The selected day's reference value is divided by the mean reference over your entered cycle length, limited to the 40 published days. This relative factor scales the average per-act estimate; it does not move the peak to a fixed number of days before your next period. This scaling is a modeling approximation, not a measured individual probability. Dates before the entered period or after day 40 use an average estimate without a cycle-day adjustment. Passing your usual cycle length does not confirm that a new period began.
If additional hormonal contraception, an IUD, sterilization or lactational amenorrhea is selected, no natural-cycle factor is applied. The underlying method estimate is used instead. The reference study describes unprotected intercourse; applying its relative timing pattern to a condom estimate is a modeling approximation, not a measured condom-failure probability.
Annual contraceptive failure rates are not per-encounter probabilities. Converting them and adjusting for personal factors requires assumptions; the displayed percentage is approximate. The model includes typical/perfect use and additional methods; results are capped at 40%.
Important
This tool estimates risk based on user inputs and research on contraceptive effectiveness. It does not diagnose or replace care from a clinician.