How to use the Due Date Calculator
Estimate a due date from a period, conception date, ultrasound, IVF transfer, or existing due date. It includes Last menstrual period, Conception date, Ultrasound, IVF transfer, Existing due date workflows, so choose the one that matches the values you actually know. Use it to understand an educational estimate and the inputs behind it, not as a diagnosis or treatment decision.
Step by step
- For the Due Date, enter first day of your last period, average length of your cycles, conception date, ultrasound date, ultrasound week. Keep each value in the unit displayed beside its field.
- Review the selected Due Date workflow and inputs, then read estimated due date in the result panel.
- Change one Due Date assumption at a time to compare scenarios. Use Reset to restore this tool's worked example values.
How the calculation works
280-day gestational dating with cycle adjustment and equivalent conception, ultrasound, and IVF calculations.
Worked example
In the Due Date worked example, first day of your last period 2026-01-01, average length of your cycles 28 days, conception date 2026-01-15, ultrasound date 2026-03-26 produces estimated due date of October 8, 2026. Based on the last menstrual period. Review the displayed units before comparing the result.
Understanding the result
The Due Date reports estimated due date. Use it to understand an educational estimate and the inputs behind it, not as a diagnosis or treatment decision. Educational estimate only; it cannot diagnose a condition or replace advice from a qualified health professional.
How to check the answer
Check the Due Date estimate by confirming the units and supported ranges for first day of your last period, average length of your cycles, conception date. Compare estimated due date with another published method or direct measurement when available, and ask a clinician before using it for a health decision.
Common questions
What does the Due Date calculate?
Estimate a due date from a period, conception date, ultrasound, IVF transfer, or existing due date.
Which Due Date inputs have the biggest effect?
estimated due date responds directly to first day of your last period, average length of your cycles, conception date, ultrasound date, ultrasound week. Change one input while holding the others constant to see its effect.
Is the Due Date result exact?
Educational estimate only; it cannot diagnose a condition or replace advice from a qualified health professional. Recheck first day of your last period, average length of your cycles, conception date and use estimated due date only for a decision where that level of precision is appropriate.