Pregnancy due date calculator
Your last period, a conception or transfer date, or a known due date gives your due date and week.
- Runs on your device
- No sign-up
- Works offline after a visit
Cycle length is usually 21 to 45 days. Leave it at 28 if you are not sure.
Pins: the 12-week and 20-week scans, full term, and a thin line for today. Scan timing varies by clinic and country.
Week by week dates
Estimates only, not medical advice. Your midwife, doctor or fertility clinic sets your dates. A scan in early pregnancy can change the due date, and so can a clinic’s own record.
How to work out a due date
- Pick what you know: the first day of your last period, the conception date, an IVF transfer or a due date from a scan.
- Enter the date, and for a last period your cycle length if it is not 28 days.
- Read your due date, your week and trimester, the full-term window and the 40-week timeline.
Questions
How is a due date worked out from the last period?
It is 280 days, or 40 weeks, after the first day of the last period, for a 28-day cycle. For a longer or shorter cycle the date moves by the difference from 28 days. Most babies arrive between 37 and 42 weeks, so the due date is an estimate.
What are the full-term weeks?
ACOG counts 39 weeks 0 days to 40 weeks 6 days as full term. Early term is 37 weeks 0 days to 38 weeks 6 days, late term is 41 weeks 0 days to 41 weeks 6 days, and post-term starts at 42 weeks 0 days. These labels describe when a baby is born, not a due date.
How is the due date worked out after IVF?
Counted from the transfer date, a day 3 embryo is due 263 days later and a day 5 blastocyst 261 days later. A due date your fertility clinic has recorded takes priority over any calculator.
Are the trimesters the same everywhere?
No. This tool uses ACOG: the first trimester runs to 13 weeks 6 days, the second from 14 weeks 0 days to 27 weeks 6 days, and the third from 28 weeks. The NHS uses different week ranges on its pregnancy pages, so ask your midwife which dates they use for your care.
Reviews
No reviews yet. Be the first.