Due Date Calculator
Calculate your estimated due date and pregnancy timeline. Enter your last menstrual period (LMP) or conception date to automatically calculate due date, current week of pregnancy, and trimester.
Result
Estimated Due Date
-
- Current Week
- 0 weeks pregnant
- Trimester
- -
Formula & Guide
Formula
L
From LMP
Due Date = LMP + 280 days
Add 280 days (40 weeks) to first day of last period
C
From Conception
Due Date = Conception + 266 days
Add 266 days (38 weeks) to conception date
Formula Variables
LMP
Last Menstrual Period
The first day of your last menstrual period
C
Conception Date
The date of conception (if known)
DD
Due Date
Estimated due date (LMP + 280 days or Conception + 266 days)
Step-by-Step Scenario
Example Scenario
LMP
January 1, 2024
1
Add 280 Days
- 280 days = 40 weeks = 9 months + 1 week
Add 280 days (40 weeks) to the LMP date
2
Calculate Due Date
- January 1, 2024 + 280 days
Additional Examples
Early Pregnancy
LMP: March 1, 2024
Due Date
December 6, 2024
Weeks Pregnant
Current week
Conception Method
Conception: January 15, 2024
Due Date
October 7, 2024
Characteristics of Due Date Calculation
Two Methods
Calculate from LMP (280 days) or conception date (266 days). LMP method is most commonly used by healthcare providers.
Pregnancy Timeline
Shows current week of pregnancy, trimester (1st, 2nd, 3rd), and estimated due date. Comprehensive pregnancy tracking.
Estimate Only
Due dates are estimates. Only 4% of babies are born exactly on due date. Most are born within 2 weeks before or after.
Full-Term Range
Full-term is 39-40 weeks. Babies born 37-42 weeks are considered full-term. Earlier than 37 weeks is preterm.
Important Notes
- Only about 4% of babies are born exactly on their due date. Most babies are born within 2 weeks before or after the due date.
- Full-term pregnancy is considered 39-40 weeks (273-280 days). Babies born between 37-42 weeks are considered full-term.
- Ultrasound dating can be more accurate in early pregnancy (first trimester). Later ultrasounds may be less accurate for dating.
- LMP method: Add 280 days (40 weeks) to the first day of your last menstrual period. This is the standard method used by healthcare providers.
- Conception method: Add 266 days (38 weeks) to the conception date. This method is less commonly used as conception date is often unknown.
Frequently Asked Questions
Find answers to common questions about due date calculation.