Pregnancy due date estimate
Enter your values to see the result, check the formula and copy your calculation.
Enter your values, then calculate.
Your calculation stays in your browser.
The formula, explained
estimated date = last period + weeks×7 + (cycle − 28)This is an indicative date, not a prediction of the birth day. Pregnancy length varies and ultrasound dating may change the estimate. Confirm your due date with your midwife or doctor.
Source and reference : NHS ↗
How to use this tool
Check the required inputs: first day of your last period, usual cycle length.
Choose the units and options that match your task. Calculate, check the result and use Copy or Print to keep a record. Rounding applies to the display; keep more precision in intermediate steps.
Can I use a decimal comma?
Yes. Numeric fields accept 12.5 or 12,5 and spaces for thousands, such as 1 234.50. Do not mix a point and comma in one number.
Where are my inputs processed?
Calculations run in your browser. Form values are not sent to Analytics. Copying, printing, sharing or opening an external service is your choice.
Method and interface checked on 2026-09-12 · Report an error