Free pregnancy tool
Due date calculator
Enter the first day of your last period to estimate your baby’s due date, your current week and the milestones ahead.
Your estimated due date will appear here.
Your estimated due date
Milestones
Estimates only. This tool gives a general estimate based on the information you enter. It is not a diagnosis or medical advice. Please consult your doctor to confirm dates and for personal guidance. Nothing you enter is sent anywhere: the calculation runs in your browser.
How your due date is estimated
Doctors count a pregnancy from the first day of your last menstrual period (LMP), not from the day of conception. A full-term pregnancy is about 40 weeks, or 280 days, from that date. Adding 280 days to your LMP is known as Naegele’s rule.
If your cycles are regularly longer or shorter than 28 days, ovulation probably happens later or earlier than the textbook day 14. This calculator shifts your date by the same number of days to reflect that.
Why it is only an estimate
- Only a small share of babies arrive on the exact due date. Most are born in the weeks around it.
- Irregular periods or an uncertain LMP make the date less reliable.
- An early ultrasound can refine the date, and your doctor may change it.
Once you know you are pregnant, a first antenatal visit is the best way to confirm your dates. Read our guide to antenatal care to know what to expect.
Talk to a doctor
A calculator cannot replace a check-up. Our team can confirm your dates and plan your care.
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Frequently asked questions
How is the due date calculated?
This calculator uses Naegele’s rule: it adds 280 days (40 weeks) to the first day of your last menstrual period. If your cycle is longer or shorter than 28 days, the date moves by the same number of days.
How accurate is an estimated due date?
Only a small share of babies are born on the exact due date. Most arrive in the weeks around it. Your doctor may adjust the date after an ultrasound.
What if I do not remember my last period?
Your doctor can estimate dates from an early ultrasound. Book a visit and our team will help you confirm your dates.
Is my information saved or sent anywhere?
No. The calculation runs entirely in your browser and nothing you enter leaves your device.
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