Ovulation
Estimate ovulation from the last period date and cycle length. Use this free ovulation for fast, clear results with no signup required.
Ovulation guide
What it is for
The Ovulation provides a planning estimate from the information entered.
How it is calculated
Estimated ovulation date = last period start + cycle length − 14 days. Cycle length must be an integer from 15 to 60 days; the model assumes a 14-day luteal phase.
Assumptions
It assumes the date and cycle length are known; real cycles and dates vary.
Example
For January 1, 2026 and a 28-day cycle, estimated ovulation is January 15, 2026. Actual timing can differ; do not use this as contraception.
Limitations
This is an educational estimate, not a diagnosis, treatment, or dosing instruction. Consult a licensed healthcare professional, particularly during pregnancy, with symptoms, or before changing health behavior.
Public source: ACOG: Due Date Calculator