Why is chance highest around cycle day 13–14?

In a typical cycle, ovulation happens near the middle of the cycle. Conception probability usually peaks around ovulation and is much lower on non-fertile days.

What does 'combined chance' mean?

If there are multiple intercourse events, the total chance is not a simple sum. The calculator uses the standard combined probability formula to avoid overestimating.

Does contraception make chance zero?

No method except complete abstinence is 100% effective. The calculator adjusts by typical-use failure factors, so probability can become low but not exactly zero.

Is this a diagnosis of infertility or guaranteed conception?

No. This is a statistical estimate for education. Real-world outcomes vary due to ovulation timing, sperm parameters, cycle variation, and health conditions.

Pregnancy Chance Calculator

Estimate your odds of conceiving this cycle from cycle-day timing, age, contraception method, and number of intercourse events.

Pregnancy Chance Estimator

Estimate conception odds per cycle from timing, age, contraception, and number of intercourse events.

Female Age

Cycle Day of Intercourse

Intercourse Events

Contraceptive Method

Factor 1.0

Estimated Combined Chance This Cycle

27%conception probability estimate

Chance band: High

Baseline (cycle day)

30%

Age-adjusted

27%

Per event chance

27%

Typical fertile-window baseline by cycle day

Cycle day	Baseline chance
Day 9	8%
Day 10	14%
Day 11	20%
Day 12	26%
Day 13	30%
Day 14	30%
Day 15	22%
Day 16	12%
Day 17	6%

Age factor

×0.9

Method factor

×1

Cycle-day baseline chances assume a typical ovulatory cycle with peak fertility near day 13–14.
Age and contraception effects are simplified multipliers derived from population-level averages.
Multiple intercourse events are combined with 1 − (1 − p)^n.

This estimate is educational and not a medical diagnosis or contraception guarantee. For personalized family-planning advice, consult your clinician.

Written by

Ashok Kumar Poudel

Health & Wellness Writer

Medically reviewed by

MBBS, MD — Gynecologist & Obstetrician

Last reviewed:

Feb 2026

How Conception Odds Are Estimated

Fertility depends heavily on timing in the menstrual cycle. In a typical ovulatory cycle, the chance of conception is highest near ovulation and lower outside the fertile window. This calculator combines cycle-day timing with age and contraception effects to estimate probability.

Formula used

Chance = Base cycle-day fertility × age factor × contraception factor × events (combined)

At low probabilities, multiple events roughly scale chance upward, but the correct combined formula is 1 − (1 − p)^n. That is what this tool uses for the final combined chance.

Reading your result

The output shows baseline chance for that cycle day, age-adjusted chance, per-event chance with selected contraception, and the final combined chance for your selected number of events. Results are grouped into low, medium, high, or very high bands for quick interpretation.

Important note

This is an educational probability model based on population averages, not a personalized diagnosis. Individual fertility can differ based on ovulation variability, sperm quality, reproductive health conditions, and clinical treatment.

Frequently Asked Questions

Common questions answered by our medical team

The tool uses a cycle-day baseline fertility estimate, applies an age factor, applies a contraception-method factor, and then combines multiple intercourse events using 1 − (1 − p)^n.

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