Baby & family
Due Date Calculator
Estimate your due date and see how far along you are today, plus the milestones coming up.
Estimated due date
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An estimate only. Only about 1 in 20 babies arrive on their due date. Your doctor or midwife may adjust it after an ultrasound. Not medical advice.
How it's calculated
Due date = First day of last period + 280 days (+ cycle length − 28)
From conception: + 266 days · IVF: transfer date + 261 (day 5) or + 263 (day 3)
From conception: + 266 days · IVF: transfer date + 261 (day 5) or + 263 (day 3)
Worked example
A last period starting March 1, 2026 with a 28-day cycle gives a due date of December 6, 2026.
How due dates are calculated
- Last period: 280 days (40 weeks) after the first day of your last period, adjusted if your cycle is longer or shorter than 28 days.
- Conception: 266 days (38 weeks) after conception.
- IVF: 261 days after a day-5 embryo transfer, or 263 days after a day-3 transfer.
Pregnancy is counted from the first day of your last period, so you're considered about 2 weeks pregnant at conception.