Free due date calculator
When Might Baby Arrive?
Pop in the first day of your last period, your conception date or just the month, and we will work out your estimated due date, trimester dates and key milestones.
- Takes 10 seconds
- Trimester dates and milestones
- Copy your result
Due date calculator
However you are counting.
One calculator, three ways in
Three ways in
Your last period, your conception date, or just the month.
Key dates mapped
Your scans, jabs, trimesters and when full term begins.
Plan ahead
Try any future month to see when baby would arrive.
The quick month-by-month chart
| Conception month | Leads to | Estimated due month |
|---|---|---|
| January | October | |
| February | November | |
| March | December | |
| April | January | |
| May | February | |
| June | March | |
| July | April | |
| August | May | |
| September | June | |
| October | July | |
| November | August | |
| December | September |
A simple month-by-month estimate based on a typical 40-week pregnancy. Your dates may vary.
How your due date is calculated
Most due dates are worked out from the first day of your last period. Add 280 days (40 weeks) and you have your estimated due date. If your cycle is longer or shorter than 28 days, the date shifts to match.
If you know the day you conceived, add 266 days (38 weeks) instead. For a typical 28-day cycle, both methods land on the same date.
The month-by-month chart above is the quick version: add nine months to your conception month to find the month your baby is due. Conceive in January and you are looking at October; conceive in June and it is March.
Due date questions
How accurate is an estimated due date?
It is an estimate. Only around 1 in 20 babies arrive on their exact due date, and most arrive between 37 and 42 weeks. A dating scan may move your date, and your midwife or doctor will confirm it.
Why is pregnancy counted from my last period and not from conception?
Pregnancy is counted from the first day of your last period, which is around two weeks before conception. That is why a pregnancy lasts 40 weeks when counted from your last period, but only about 38 weeks from conception.
What if I am not sure of my dates?
Use the last period option if you can remember the date, and adjust your cycle length if it is not 28 days. If you are unsure of both, a dating scan gives the most accurate date.
When will I have my first scan?
In the UK, the first (dating) scan is usually offered between 10 and 14 weeks, often around week 12, and the mid-pregnancy scan between 18 and 20 weeks. Your result lists both windows worked out from your due date. Your hospital will send your exact appointments.
What does the month-only option show?
It shows the month your baby is due if you conceive in a given month, plus the full range of due dates for that month. Pick a future month if you are planning ahead.
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