Due Date Calculator
Calculate your estimated due date based on your last menstrual period, conception date, or IVF transfer date. Track your pregnancy week by week and see important pregnancy milestones.
Key Pregnancy Dates & Timeline
| Milestone | Gestational Age | Your Date |
|---|---|---|
| Enter a date to see your timeline | ||
About Due Date Calculator
Knowing your estimated due date is one of the first things expectant parents want to know. While due dates are estimates (only about 5% of babies arrive exactly on their due date), they help you prepare for your baby's arrival and track your pregnancy progress.
This calculator uses Naegele's Rule, the standard method used by healthcare providers to estimate due dates. It adds 280 days (40 weeks) to the first day of your last menstrual period.
How Due Date Calculator Works
- Last Menstrual Period (LMP): The most common method. Adds 280 days to the first day of your last period.
- Conception Date: If you know when you conceived, adds 266 days to that date.
- IVF Transfer Date: For assisted reproduction, adjusts based on embryo age at transfer.
- Gestational Age: Calculated from LMP, measured in weeks and days.
- Trimester: Pregnancy is divided into three 13-week periods.
What This Calculator is Good For
- Pregnancy Planning: Determine when to expect your baby.
- Medical Appointments: Schedule prenatal care and ultrasounds.
- Preparation Timeline: Plan nursery setup, baby showers, and time off work.
- Fetal Development Tracking: Understand what's happening at each stage.
- Trimester Tracking: Know which trimester you're in and what to expect.
- Risk Assessment: Identify early or late pregnancy for medical monitoring.
Limitations & Considerations
- Estimates Only: Due dates are estimates; only 5% of babies arrive on their exact due date.
- Irregular Cycles: This calculator assumes a 28-day cycle; adjust if yours is different.
- Multiple Pregnancies: Twins and multiples typically deliver earlier than singleton pregnancies.
- Medical Factors: Certain conditions may affect delivery timing.
- Ultrasound Accuracy: Early ultrasounds are more accurate than LMP calculations.
- Not Medical Advice: Always confirm dates with your healthcare provider.
Due Date Calculation Formula
Due Date = First day of LMP + 280 days (40 weeks)
From Conception Date:
Due Date = Conception Date + 266 days (38 weeks)
From IVF Transfer:
Due Date = Transfer Date + 266 days + (Embryo Age)
Gestational Age Calculation:
Gestational Age (weeks) = (Today - LMP) ÷ 7
Gestational Age (days) = (Today - LMP) mod 7
Frequently Asked Questions
Your healthcare provider can estimate your due date using an early ultrasound, which is actually more accurate than LMP calculations. First-trimester ultrasounds are accurate within 3-5 days.
Yes, babies can arrive anytime after 37 weeks and be considered full-term. Delivery before 37 weeks is considered preterm. Your healthcare provider will monitor for early labor signs.
If your cycle is irregular, an ultrasound is more reliable for dating. Discuss your cycle length with your healthcare provider for the most accurate due date.
Most healthcare providers recommend scheduling your first prenatal visit around 8-10 weeks of pregnancy. This is when an ultrasound can confirm your due date.
These terms are used interchangeably. Both refer to the estimated date your baby will be born, calculated as 40 weeks from the first day of your last menstrual period.