Due Date Calculator
Estimated delivery date and pregnancy milestones.
Enter your values
ⓘ Live results
Results
- Estimated due date
- 2026-12-06 (Sunday)
- Gestational age today
- 21 weeks, 2 days
- Trimester
- Second
- Conception (approx)
- 2026-03-15
- Days remaining
- 131
Quick answer
Naegele's rule estimates the due date as 280 days from the first day of the last menstrual period.
Due date = LMP + 280 days
How to use the Due Date Calculator
- 1Enter the first day of your last period.
- 2Adjust your average cycle length.
- 3Read the due date and current gestational age.
Worked example
Using the values the calculator loads with:
Inputs
- First day of last period2026-03-01 YYYY-MM-DD
- Cycle length28 days
- Today's date2026-07-28 YYYY-MM-DD
Results
- Estimated due date2026-12-06 (Sunday)
- Gestational age today21 weeks, 2 days
- TrimesterSecond
- Conception (approx)2026-03-15
- Days remaining131
Frequently asked questions
How accurate is the due date?
Only about 4% of babies arrive on the estimated date; roughly 80% arrive within two weeks either side.
Why count from the last period?
Ovulation is hard to pin down, but the last period is a date most people know, so obstetrics standardised on it.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.