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Use this pregnancy due date calculator for a clear health & fitness estimate. Results update instantly in your browser.
What this calculator does
Estimate a due date from the first day of the last menstrual period.
How to use this calculator
- Enter the relevant start date.
- Review the calculation assumptions before using the result.
- The date is a planning estimate, not a guarantee.
How to calculate
Estimated due date = first day of last period + 280 days + (cycle length − 28 days).
Enter the values requested by the pregnancy due date calculator.
Worked example
Use the default values as a worked example, then replace them with your own figures.
Understanding your result
The date is a planning estimate, not a guarantee.
- Cycle length and clinical dating can change it.
- Double-check values and units before calculating.
This calculator is educational and is not financial or medical advice.
Frequently asked questions
What does this pregnancy due date calculator do?
Estimate a due date from the first day of the last menstrual period.
How do I use this pregnancy due date calculator?
Enter the relevant start date.
What does the result mean?
The date is a planning estimate, not a guarantee.
What should I check before relying on it?
Cycle length and clinical dating can change it.