Pregnancy Due Date Calculator
Estimate pregnancy due date from the first day of the last menstrual period.
Calculator updated
Use this page to get a quick answer, then check the formula and example before making an important decision.
- The main result from your inputs
- Formula used for the calculation
- Worked example and common mistakes
- Related calculators for the next step
Formula
Estimated due date = first day of last menstrual period + 280 days.
LMP on Jan 1 gives an estimated due date around Oct 8.
Enter the measurements requested by the form and apply Estimated due date = first day of last menstrual period + 280 days.. Use consistent measurement conditions when comparing results over time.
Use the Pregnancy Due Date Calculator as a general wellness or fitness estimate. It is not a diagnosis and should not replace professional medical advice.
Common health-calculation errors include inaccurate measurements, changing measurement conditions between checks, treating population formulas as diagnoses, and over-interpreting small differences.
Examples
Inputs
First day of last menstrual period
Keep units and time periods consistent.Formula
Estimated due date = first day of last menstrual period + 280 days.
Use the formula to verify the result.What the result means
Estimate pregnancy due date from the first day of the last menstrual period.
Change one input at a time to compare scenarios.How to Calculate Pregnancy Due Date Manually
Start with the values requested in the form, keep the units consistent, and apply this formula: Estimated due date = first day of last menstrual period + 280 days.
The calculator above follows the same logic, then formats the answer so you can quickly compare inputs, copy the result, and check the related tools if your task has another step.
When to Use This Calculator
- Track a general wellness estimate
- Compare measurements over time
- Support fitness planning
- Prepare questions for a qualified professional
How It Works
- Enter First day of last menstrual period.
- Use accurate, consistently taken measurements.
- Review the result as an estimate and read any limitations on the page.
Common Mistakes
- Using inaccurate measurements
- Changing measurement conditions
- Treating an estimate as a diagnosis
- Over-interpreting small changes
Related Calculators
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Continue the same workflow with closely related calculators.
Frequently Asked Questions
What does the Pregnancy Due Date Calculator do?
Estimate pregnancy due date from the first day of the last menstrual period.
Is this result an estimate?
Yes. The calculator follows the formula shown on the page. Verify important decisions with a qualified professional where needed.
Can I use this on mobile?
Yes. The calculator is designed to work on phones, tablets, and desktop screens.