Conception Date Calculator
Conception calculator: estimate when conception happened from the due date (or birth date), with the likely window and the date of the last period.
conception ≈ due date − 266 days
How to use this calculator
- Type your input in the box.
- The result updates as you type.
- Use “Copy result” or “Copy link” to share it.
Conception usually happens about 266 days (38 weeks) before the due date, around ovulation. Most babies are born within two weeks of the due date, so the result is an estimate.
For general information only; it does not replace advice from a doctor or other health professional.
Frequently asked questions
Due date September 30, 2026?
Conception most likely around January 7, 2026.
Related calculators
- Lean Body Mass Calculator
- Waist-to-Hip Ratio Calculator
- Waist-to-Height Ratio Calculator
- Body Surface Area Calculator (BSA)
- Period Calculator (Next Period Date)
- Steps to Miles Calculator
- Blood Sugar Converter (mg/dL ⇄ mmol/L)
- A1C Calculator (A1C to Average Blood Sugar)
Last updated: · Report an error