Due Date Calculator

Estimate an expected due date using the standard 280-day method, adjusted for cycle length. This is an estimate, not a confirmation of pregnancy.

Health information notice: Results are estimates based on general formulas and may not reflect individual circumstances. This tool is not a diagnosis or substitute for personalized advice from a qualified healthcare professional.

How the due date calculator works

Estimated due date = first day of the last menstrual period + 280 days + (cycle length − 28 days).

Formula and assumptions

Estimated due date = first day of the last menstrual period + 280 days + (cycle length − 28 days).

Example

Try the sample values, then change one input at a time to see how the result changes. Check that units match the labels.

Important limitations

Due dates are estimates; many babies are born before or after the estimated date. A clinician may adjust dating using menstrual history and ultrasound.

Frequently asked questions

What does this calculator do?

What does this calculator estimate? Estimate an expected due date using the standard 280-day method, adjusted for cycle length. This is an estimate, not a confirmation of pregnancy.

What should I know about the result?

Due dates are estimates; many babies are born before or after the estimated date. A clinician may adjust dating using menstrual history and ultrasound.

Results are estimates for general information only. They are not a substitute for professional advice where applicable. Found a mistake? Report an error.