Pregnancy Due Date Calculator
Estimate your baby's due date from the first day of your last period, the conception date or an IVF transfer date — and see how many weeks pregnant you are.
For general information only — not medical advice. Results are estimates; talk to a doctor or qualified health professional about your own health.
How to use
- 1Choose how you want to calculate: last period, conception or IVF transfer.
- 2Enter the date (and your usual cycle length for the last-period method).
How it's calculated
Last period: due date = LMP + 280 days + (cycle length − 28). Conception: + 266 days. IVF: 3-day transfer + 263 days, 5-day transfer + 261 days. Pregnancy weeks are counted from the (adjusted) last period.
Frequently asked questions
How accurate is a due date?
Only about 4% of babies arrive on their due date; most arrive within two weeks either side. An early ultrasound gives the most accurate dating.
Why is pregnancy counted from my last period?
Ovulation dates are rarely known, but the first day of the last period usually is. So 'weeks pregnant' includes about two weeks before conception.
What if my cycle isn't 28 days?
Enter your usual cycle length and the date shifts by the difference, since ovulation happens later in longer cycles.