Pregnancy Risk Information Tool
Estimate pregnancy risk from a single act, by cycle day and method. Free, private and instant.
How to use the Pregnancy Risk Info
- Pick first day of your last period.
- Enter average cycle length (days).
- Pick date of intercourse.
- Choose method used: No method, Withdrawal (pulling out), Condom (used, no breakage), Pill, but missed one or more and more.
- Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.
About the Pregnancy Risk Info
This educational tool estimates the chance of pregnancy from one act of sex using where you were in your cycle and what contraception was used. It also explains when to consider emergency contraception and when to test.
Also known as: chance of pregnancy calculator, could I be pregnant, pregnancy probability calculator, pregnancy chance by cycle day.
Worked example
Dates in this example are worked out as if today were 5 Nov 2026.
- First day of your last period: 22 Oct 2026
- Average cycle length: 28 days
- Date of intercourse: 4 Nov 2026
- Method used: No method
Estimated chance of pregnancy: 31 % (High). Sex on 4 Nov 2026 was 1 day before your estimated ovulation (5 Nov 2026). With this method the estimated chance of pregnancy from that act is about 31%.
- Estimated ovulation: 5 Nov 2026
- Fertility on that day: 31%
- Method effect: x 1
- Test for pregnancy from: 25 Nov 2026
Formula and cut-offs
Chance on the day (approx.): 5 days before ovulation 10%, 4 days 16%, 3 days 14%, 2 days 27%, 1 day 31%, ovulation day 33%, day after 4%. Method multipliers use typical-use failure rates.
Frequently asked questions
What is the chance of getting pregnant from one time?
On average about 5% for a single act, but up to about 30% on the 2 days before ovulation.
Can I get pregnant if he pulled out?
Yes. Withdrawal fails in about 1 in 5 users each year.
What should I do if the condom broke?
Consider emergency contraception as soon as possible, and think about STI testing.
Sources and references
- World Health Organization - Family planning/contraception methods
- NHS - Contraception guide
- CDC - Sexually transmitted infections (STIs)
Written and checked by the MediHub editorial team against the sources above. Read how we build and review our calculators.
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Last updated . This calculator is for education only and is not medical advice. See the medical disclaimer.