Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Due Date Calculator

Estimates how many days remain until your due date and your current pregnancy week from how many days ago your last period (or conception/ultrasound reference) was, plus cycle length and any ultrasound adjustment.

Days Since Last Period (or chosen reference) (days)

Average Cycle Length (days)

Calculation Method

Ultrasound Adjustment (days)

Fill in the required fields to see your result.

Pregnancy

Due Date Calculator

Estimates your baby's due date by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP) using Naegele's Rule. Use it in early pregnancy to plan prenatal appointments, milestones, and parental leave.

Last Menstrual Period (days ago)

Fill in the required fields to see your result.

Key differences

	Due Date Calculator	Due Date Calculator
Category	Pregnancy	Pregnancy
Inputs required	4	1
Result	Due Date Countdown	Days until due date (days)
What it does	Estimates how many days remain until your due date and your current pregnancy week from how many days ago your last period (or conception/ultrasound reference) was, plus cycle length and any ultrasound adjustment.	Estimates your baby's due date by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP) using Naegele's Rule. Use it in early pregnancy to plan prenatal appointments, milestones, and parental leave.