Pregnancy Due Date Calculator

This calculator estimates when your baby is due and turns that one date into a full picture: how many weeks and days pregnant you are, which trimester you are in, how many days are left, and a timeline of the dates that matter, from the missed period and dating scan to the anatomy scan, 24 weeks, term at 37 weeks, the due date itself and 42 weeks.

You can work it out four ways. Most people use the first day of their last period; if your cycle is longer or shorter than 28 days, pick your cycle length and the date moves to match. If you know when you conceived, use that. After IVF, enter the transfer date and whether it was a day-3, day-5 or day-6 embryo, which is usually the most exact method of all. If you have had a scan, enter its date and how far along it said, and every other date follows from it.

The sums happen in your browser, so the dates you type stay on your device and nothing is saved. Dates are shown in your own language and date order, and they are counted as whole calendar days so a clock change can never shift them. It is an estimate to help you plan, not medical advice.

1. Under “Work it out from”, choose Last period, Conception, IVF transfer or Ultrasound.
2. Enter the date it asks for. For Last period, pick your average cycle length; for IVF, the embryo age; for Ultrasound, the weeks and days the scan gave.
3. Read your estimated due date, how far along you are and your trimester on the progress bar.
4. Change “Show how far along on” to see any other day, or press Today to go back.
5. Scroll through the key dates, then press “Copy results” to paste them into notes or a message.

• Four dating methods: last period (Naegele’s rule), conception date, IVF transfer (day 3, 5 or 6 embryo) and ultrasound.
• Cycle-length adjustment from 20 to 45 days for the last-period method.
• Weeks and days pregnant, trimester and a progress bar marked at 14 and 28 weeks.
• Days to go, estimated conception date and the 37–42 week window when most babies arrive.
• A timeline of ten key dates, each marked done, now or next.
• Check how far along you will be on any date, past or future.
• Dates in your own language and order, counted safely across clock changes and leap years.
• Copy everything as plain text in one tap.

• If your period dates are hazy, an early scan dates a pregnancy more reliably. Once you have one, switch to Ultrasound and use the scan’s figures.
• Pregnancy weeks count from your last period, about two weeks before conception, so at conception you are already “2 weeks pregnant”. That is normal, not a mistake.
• Irregular cycles make the last-period method less accurate. Use your usual cycle length, or the conception or scan method if you can.
• Think of your due date as the middle of a five-week window. Plan for the whole of 37 to 42 weeks rather than one day.