Pregnancy Due Date Calculator
Estimate your baby's due date and how far along you are, from the first day of your last period. Calculated in your browser.
An estimate using Naegele's rule. Not medical advice, your doctor's dating scan is more accurate. Your inputs never leave your device.
Estimate your baby's due date and how far along you are, from the first day of your last period, using Naegele's rule.
How to use
- Pick the first day of your last menstrual period.
- Calculate to see the estimated due date and current weeks.
Frequently asked questions
How is the due date calculated?
Naegele's rule adds 280 days (40 weeks) to the first day of your last period. It's the standard estimate, though only about 1 in 20 babies arrive exactly on the due date.
How accurate is this?
It's a calendar estimate. A doctor's dating ultrasound is more accurate, especially if your cycle is irregular. This is not medical advice, consult your doctor.
What if my cycle isn't 28 days?
Naegele's rule assumes a 28-day cycle. If yours differs, your actual due date may shift; your doctor can adjust it.