How do I calculate ovulation? Enter your numbers above and the result updates instantly. For example: First day of last period: 2026-07-15 · Cycle length: 28 days → Estimated ovulation: Wed, Jul 29, 2026.
Is this Ovulation Calculator free? Yes — completely free with no sign-up or paywall. It runs entirely in your browser and keeps working offline; the numbers you enter never leave your device.
How accurate is it? It uses the standard published formula for ovulation. Results are estimates for planning — not financial, tax, medical, engineering, or legal advice.