Due Date Calculator
Result
Calculated result
2026-10-08
Based on the values entered.
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Due Date Calculator — free online calculator.
Formula
Estimated due date ≈ LMP + 280 days.
- Due Date Calculator calculates its result from Last menstrual period date. It uses the formula Estimated due date ≈ LMP + 280 days.. Change any input to recalculate the result instantly. This is an informational calculation and is not medical advice.
- The main inputs are Last menstrual period date. Enter them in the units and format shown in the calculator.
- Use the measurement units shown beside each field. The result is an estimate and should be interpreted in context.
- Changing any input above recalculates the result with the same calculation engine used by this page.
Example: Due Date
Inputs
- Last menstrual period date: 2026-01-01
Using Last menstrual period date = 2026-01-01, the calculated result is 2026-10-08.
Sample result: Calculating…
Frequently asked questions
What does the Due Date calculate?
Due Date Calculator — free online calculator.
Which values should I enter?
Enter Last menstrual period date using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: Estimated due date ≈ LMP + 280 days..
Why might my result differ from another source?
Results can differ because measurement methods, rounding and assumptions vary. This calculator is an estimate and is not a medical diagnosis.
Does the result update automatically?
Yes. Changing an input updates the result using the same calculation engine shown on this page.