Free health tool
Pregnancy Due Date Calculator
Private — nothing you enter is stored or sent · Updated Sep 2026
Due date, how many weeks pregnant you are, trimester and key scan dates. Free, private and instant — nothing you type is stored.
How this works
Pregnancy is counted as 40 weeks (280 days) from the first day of your last period — about two weeks before conception. If your cycle is longer or shorter than 28 days, we move the date by the difference. From a known conception date we add 266 days; from an IVF transfer we add 261 (day-5 embryo) or 263 days (day-3 embryo).
Good to know
- Only about 1 in 20 babies arrive on their due date; most come between 37 and 42 weeks.
- Your dating scan (around 11–14 weeks) gives the most accurate date and replaces this estimate.
This tool gives general information only and is not a diagnosis. Nothing you enter leaves your browser.