# Pregnancy due date calculator

> Your last period, a conception or transfer date, or a known due date gives your due date and week.

Due date from your last period, conception, IVF transfer or a scan, with your week, trimester, full-term dates and a 40-week timeline. Runs in your browser.

- Tool: [Pregnancy due date calculator](https://fixmint.cc/due-date-calculator)
- Category: [Numbers & dates](https://fixmint.cc/numbers)
- Fixes: When is my baby due?
- Runs in the browser: files and text stay on the device, no sign-up, free.

## How to work out a due date

1. Pick what you know: the first day of your last period, the conception date, an IVF transfer or a due date from a scan.
2. Enter the date, and for a last period your cycle length if it is not 28 days.
3. 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.

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