Due Date Calculator
Estimate your baby's due date from your last period, conception or IVF transfer date.
Enter your values to see the result.
These results are estimates for general information, not medical advice. Body shape, muscle mass, age, ethnicity and health conditions all affect what is right for you, so talk to a doctor or dietitian before making health decisions.
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Clear instructions
Find steps, examples and limitations below.
Use online
Open the tool in a supported web browser.
Free to use
No sign-up required. Tool-specific limits may apply.
How to use the Due Date Calculator
Estimate your baby's due date from your last period, conception or IVF transfer date.
- 1 Choose what to calculate from: last period, conception, IVF transfer or ultrasound.
- 2 Enter the date (and cycle length or scan age if asked).
- 3 Read the due date and key pregnancy dates.
Example and practical tips
With a last period starting 1 January and a 28-day cycle, the estimated due date is 8 October.
Frequently asked questions
How is the due date calculated?
Naegele’s rule adds 280 days (40 weeks) to the first day of the last period, adjusted for cycle length.
How accurate is the due date?
Only about 4% of babies arrive on the day; most come within two weeks either side. An early ultrasound is the most accurate way to date a pregnancy.
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