Pregnancy Calculator
Estimate a pregnancy due date and conception date from menstrual dating.
Estimated conception date: August 3, 2026.
Clinical ultrasound dating may change the estimate.
How to use this calculator
- Enter the first day of the last menstrual period and typical cycle length.
- Review the live result and use Copy result when you need to share it.
How the calculation works
The estimate adds 280 days to the last-period date and adjusts by cycle length relative to 28 days.
Formula
The estimate adds 280 days to the last-period date and adjusts by cycle length relative to 28 days.
Step-by-step calculation
- Enter the first day of the last menstrual period and typical cycle length.
- The estimate adds 280 days to the last-period date and adjusts by cycle length relative to 28 days.
- Check the displayed result, then copy it if needed.
Worked example
A last-period date of 20 July 2026 with a 28-day cycle estimates a due date in April 2027.
Risk guidance
Frequently asked questions
Does this tool send my inputs anywhere?
No. The interactive calculation runs in your browser and this site does not submit tool inputs to a backend.
How should I use the result?
Check that the entered units and values match your situation, especially around dates, breaks, and rounding.
Related tools
Due Date Calculator
Estimate a pregnancy due date from the last period and cycle length.
Open toolPregnancy Conception Calculator
Estimate conception and menstrual dates from an estimated due date.
Open toolPregnancy Weight Gain Calculator
Compare pregnancy weight change with broad singleton guidance ranges.
Open tool