Enter your due date, or the first day of your last period, or your conception date, and see how many days are left, how many weeks pregnant you are and which trimester you are in.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How the Due date countdown works
Everything is counted from the first day of your last period, the way pregnancy weeks are usually dated. Choose which date you know:
- Due date: the start date is 280 days (40 weeks) before it.
- Last period: the due date is 280 days (40 weeks) after it, which assumes a 28-day cycle (Naegele’s rule).
- Conception date: the start date is taken as 266 days before the due date, so the due date is 266 days after conception.
The results are then worked out for the “Count from” date, which is today by default and is shown in the results. Because they depend on that date, they change each day. The tool shows days left, weeks and days pregnant, the trimester (first to 13 weeks 6 days, second from 14 weeks, third from 28 weeks), the progress through 40 weeks, and the date full term starts at 37 weeks. Only a small minority of babies arrive on the due date, and your midwife’s scan dates take priority.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| I know my | Due date |
| Date | 2027-01-25 |
| Count from | 2026-10-05 |
Until the due date: 112 days to go
| Counted on | Mon, 5 October 2026 |
|---|---|
| Weeks pregnant | 24 weeks, 0 days |
| Trimester | Second trimester |
| Due date | Mon, 25 January 2027 |
| Time left | 16 weeks, 0 days |
| Progress | 60% of 40 weeks |
Tips and common mistakes
If your scan gave a different due date from your last period, use the scan date, because that is the one your midwife will work to. Remember the countdown is to a due date, not a deadline: most babies arrive in the weeks either side of it. Change the “Count from” date to see what week you will be on at a holiday, wedding or work milestone. Always follow your midwife’s advice about appointments and scans. This is general information, not medical advice.
Frequently asked questions
How many days are left until my due date?
Enter your due date and the calculator counts the days from today (or the date you choose) and shows them as days, and as weeks and days.
Which trimester am I in?
This tool treats the first trimester as up to 13 weeks and 6 days, the second as 14 to 27 weeks and 6 days, and the third as 28 weeks until birth.
Why does my result differ from my midwife's?
Your midwife may date the pregnancy from an ultrasound scan, which can move the due date. Use the date given at your scan if it differs from the one the calculator works out.