Due Date Calculator
Estimated due date from the first day of your last period.
Estimate a pregnancy due date
Enter the first day of your last period. The estimate uses Naegele’s rule of 280 days.
This is informational only. A clinician confirms dating with history and, when needed, ultrasound.
Cycle length and ovulation timing can shift the real due date.
due date calculator FAQ
Fill in the fields above. The result updates as you type. Empty fields stay blank until you enter a valid number or text.
Yes. Every SmartToolX calculator and converter is free. There is no paywalled result.
No. Inputs stay in your browser unless a tool needs a public API, such as live currency rates or QR image rendering.
We use the same published formulas you would expect from a standard due date calculator. Always double-check medical, legal, or large money decisions.