Due Date Calculator

Last Period

Conception Date

Ultrasound Date

First Day of Last Menstrual Period:

Average Cycle Length (days):

Conception Date:

Ultrasound Date:

Gestational Age at Ultrasound:

Your Pregnancy Progress

Enter your information to see your pregnancy progress

About Due Date Calculations

A due date is an estimate of when your baby will be born, calculated as 40 weeks (280 days) from the first day of your last menstrual period (LMP). Only about 5% of women actually deliver on their due date, but most deliver within 2 weeks before or after.

Calculation Methods:

Method	How It Works	Accuracy
Last Menstrual Period	Due date = LMP + 280 days	Good for regular cycles
Conception Date	Due date = Conception + 266 days	Accurate if you know conception date
Ultrasound	Based on fetal measurements	Most accurate early in pregnancy

Key Facts About Due Dates:

• Pregnancy typically lasts 37-42 weeks
• Babies born before 37 weeks are considered premature
• Babies born after 42 weeks are considered post-term
• First pregnancies often last slightly longer
• Your healthcare provider may adjust your due date based on ultrasound findings

What Affects Due Date Accuracy?

• Irregular menstrual cycles
• Incorrect recall of LMP date
• Late or early ovulation
• Multiple pregnancies (twins, etc.)