How do you calculate weeks pregnant from LMP?

We count whole days from your LMP date (UTC) to today (UTC), then convert to weeks and remaining days.

Why do you use UTC for pregnancy calculations?

UTC avoids off-by-one errors from time zones and daylight saving time changes.

No. This tool is informational only. Always follow your healthcare provider’s guidance.

Enter the first day of your last menstrual period (LMP) to estimate your pregnancy in weeks and days. This calculator is UTC-safe.

Can I use this if I have irregular cycles?

You can, but accuracy may vary. Many providers adjust dates using ultrasound measurements.

Does this estimate my due date?

This page focuses on weeks + days pregnant from LMP. If you already have an EDD, use Weeks Until Due Date or Days Until Due Date.

Why does my app show something different?

Different tools use different assumptions (e.g., cycle length, rounding, local time vs UTC). We use whole-day UTC boundaries for consistency.