Ovulation Calculator
Predict your fertile window and ovulation days.
Estimated ovulation
2026-07-15
- Fertile window
- 2026-07-10 → 2026-07-16
- Next period expected
- 2026-07-29
- Cycle
- 28 days
How this is calculated
ovulation ≈ last period + (cycle − 14)
2026-07-01 + (28 − 14) days = 2026-07-15
The fertile window spans the 5 days before ovulation through the day after.
Cycles vary — this is an estimate, not a guarantee of the fertile days.
Computed on your device — nothing is sent anywhere.
How it works
Predict your fertile window and ovulation days. Runs 100% in your browser, so your files never leave your device. Free, fast, no signup.
Questions about ovulation calculator
Yes — no watermark, no daily cap, no signup. Pro raises the file-size and batch limits, but the tool itself is not gated.
No. This tool runs entirely in your browser. Open your network inspector and watch while it works — there are no file uploads, because there is no upload endpoint.
Up to 10 files at 15 MB each. Everything runs in your browser, so the real ceiling is your device’s memory — the cap keeps a large file from exhausting the tab.