Health calculators
Ovulation Calculator
Estimate ovulation and a fertile window from last period date and average cycle length. Not contraception or medical advice.
Estimates only — not medical advice. Formulas are simplified screening tools. Talk to a qualified clinician for health decisions.
Est. ovulation
2026-06-15
Fertile window
2026-06-10 → 2026-06-16
How to use
- Enter LMP date and typical cycle length.
- Read estimated ovulation day.
- See an approximate fertile window around ovulation.
Features
- Cycle-length based estimate
- Fertile window range
- Local date math
Privacy & how it works
This calculator runs entirely in your browser with JavaScript. Your inputs are not uploaded to ToolsWeb servers for this tool. Privacy Policy · Disclaimer.
FAQ
Can I use this for birth control?expand_more
No. Cycle apps and calendars are unreliable for contraception. Use clinician-recommended methods.
Is this calculator free?expand_more
Yes. No signup required.
Are my numbers uploaded?expand_more
No. Calculations run in your browser. Inputs are not sent to ToolsWeb servers for this tool.
Is this professional advice?expand_more
No. Results are estimates for general information. See our Disclaimer for health, finance, and related tools.