How to use the Due Date Calculator
The due date calculator estimates a due date from your last period, conception date or an IVF transfer.
Open the Due Date Calculator →
What you need to enter
- Based on
- Date
The formula
Last period + 280 days; conception + 266 days; day-5 embryo transfer + 261 days.
Worked example
Using the default values in the calculator:
- Based on: First day of last period
- Date: 2026-10-13
| Estimated due date | Tue, 20 Jul 2027 |
| Conception around | Tue, 27 Oct 2026 |
Tips for better results
- Confirm with your midwife or doctor.
- Different methods can differ by days.
Common mistakes to avoid
- Mixing up conception and last-period dates.
- Ignoring scan dating.
Please note: Health calculators and guides give general estimates, not medical advice. Talk to a doctor or other qualified professional about your own health. See our Disclaimer.