Pregnancy Due Date Calculator
Estimate your due date and current week of pregnancy from your last menstrual period.
Inputs
Saved Scenarios
— select 2+ to compare| Metric | |
|---|---|
Estimated Due Date
2027-04-16
Weeks Pregnant
0
Days Until Due
280
Spark says
What is the Pregnancy Due Date Calculator?
This calculator uses Naegele's rule — adding 280 days (40 weeks) to the first day of your last menstrual period — to estimate a due date.
How to use it
- 1 Enter the first day of your last menstrual period.
Worked examples
Limitations
- •An estimate based on a standard 28-day cycle — actual due dates vary, and an ultrasound dating scan is more precise for irregular cycles.
- •Not a substitute for medical advice — always confirm with a healthcare provider.
Frequently asked questions
How accurate is a due-date estimate from the last period?
It assumes a regular 28-day cycle with ovulation on day 14 — for irregular cycles, an early ultrasound typically gives a more accurate estimate.