Pregnancy Due Date Calculator
Due date from a period, a scan or an IVF transfer.
Pregnancy Due Date Calculator estimates a due date from the last menstrual period, a conception date, an IVF transfer or a dating scan. It shows the current gestational age in weeks and days, the trimester and every milestone date, and adjusts for cycles longer or shorter than 28 days. Nothing you type is uploaded.
Loading Pregnancy Due Date Calculator…
Runs entirely on your device. No file or text you enter here is uploaded. How to verify it.
This is a calculation tool, not medical advice. The result is an estimate from a published formula and cannot account for your individual circumstances. Talk to a healthcare professional about anything that matters.
How to use Pregnancy Due Date Calculator
- Choose the date you know: last period, conception, IVF transfer or scan.
- Enter that date, and your usual cycle length if you are dating from a period.
- Read the estimated date, the gestational age today and the milestone table.
Questions about Pregnancy Due Date Calculator
How likely is a birth on the estimated date?
About one in twenty. The date is the middle of a spread, not an appointment, and a term birth is anything from 37 weeks to 41 weeks and 6 days — a five-week window. It is worth having because antenatal care is scheduled by gestational age, not because that particular day is probable.
Why does cycle length change the answer?
Naegele rule adds 280 days to the first day of the last period and assumes a 28-day cycle with ovulation on day 14. A longer cycle means ovulation happened later, so the pregnancy is younger than the period suggests. The tool adds the difference between your cycle and 28 days, which moves a 35-day cycle a week later.
Which method is the most reliable?
A first-trimester ultrasound. Early foetal measurements vary less between pregnancies than cycles vary between people, so where a scan before about 14 weeks disagrees with the last period by more than roughly a week, maternity services date from the scan. Later scans lose that edge — by the third trimester a scan can be out by a fortnight either way.
Why does the pregnancy start two weeks before conception?
Because gestational age is counted from the first day of the last period, which is a date people can usually remember, unlike the date of ovulation. That convention makes a pregnancy two weeks old on the day it begins, and it is why 40 weeks of gestation contains only about 38 weeks of actual growth.
Is anything I enter here kept?
Not the dates. They are read by JavaScript in your own tab, used to fill in the arithmetic, and never written to storage or sent anywhere, because a due date is health information about two people. Two things are remembered on this device so the page opens the way you left it: which dating method you picked, and the cycle length. Nothing leaves the browser either way.
Is Pregnancy Due Date Calculator really free, with no limits?
Yes. There is no account, no daily cap, no file-size tier and no watermark, because there is no server cost to recover. The site is funded by clearly disclosed partner recommendations on the Partners page, never by metering the tools.
Are my files or text uploaded when I use Pregnancy Due Date Calculator?
No. Everything is processed by JavaScript running in your browser, on your device. You can verify it: open your browser's developer tools, switch to the Network tab, and use the tool. You will see no request carrying your data — because there is nowhere for it to go.