Conception Date Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter details
Result
Enter a date to see your estimate.
Estimate only — not medical advice. Due dates, ovulation and fertile windows vary between people and cycles. Confirm with a healthcare professional.
How to use this calculator
- Choose to work from your last period or a due date.
- Enter the date.
- Read the estimated conception date and window.
How it works
Conception is about 14 days after the last period, or 266 days before the due date. A few-day window reflects sperm survival and ovulation timing.
Worked example
Due 8 Oct 2026. Estimated conception ≈ 16 Jan 2026.
Tips
- Estimate only — not medical advice. Dates and fertile windows vary between people and cycles; confirm with a healthcare professional.
Frequently asked questions
Can it pinpoint the exact day?
No — it gives a likely window; exact conception is rarely known.
Privacy?
Runs entirely in your browser. Your inputs are not saved or transmitted.
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.