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đļ Due Date Calculator
Calculate your pregnancy due date and track your journey
đ Enter Your Information
âšī¸ Enter the first day of your last menstrual period. This is the most common method used by healthcare providers.
đ Your Results
Estimated Due Date
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Conception Date
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Days Until Due Date
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Current Trimester
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Weeks Pregnant
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đą First Trimester
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đŋ Second Trimester
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đŗ Third Trimester
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đ Enter Your Information
âšī¸ If you know the exact date of conception, enter it here. This method adds 266 days to calculate your due date.
đ Your Results
Estimated Due Date
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LMP Date
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Days Until Due Date
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Current Trimester
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Weeks Pregnant
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đą First Trimester
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đŋ Second Trimester
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đŗ Third Trimester
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đ Understanding Pregnancy Due Dates
What is a Due Date?
A due date, also called an estimated delivery date (EDD), is the date when your baby is expected to be born. It's calculated as 40 weeks (280 days) from the first day of your last menstrual period (LMP). Only about 5% of babies are born on their exact due date, but it provides an important reference point for tracking your pregnancy.
How is the Due Date Calculated?
Naegele's Rule (LMP Method): Add 280 days (40 weeks) to the first day of your last menstrual period. This assumes a 28-day menstrual cycle with ovulation occurring on day 14.
Conception Date Method: If you know the exact conception date, add 266 days (38 weeks) to calculate the due date. This method is more accurate if you're certain of the conception date.
Pregnancy Trimesters
- First Trimester (Weeks 1-13): Early development, morning sickness, fatigue, and rapid fetal growth
- Second Trimester (Weeks 14-27): Energy returns, baby movements felt, anatomy scan performed
- Third Trimester (Weeks 28-40): Final growth, preparation for birth, increased discomfort
Factors Affecting Due Date Accuracy
- Irregular cycles: If your menstrual cycle isn't 28 days, the calculation may be less accurate
- Uncertain LMP: Not remembering the exact date can affect accuracy
- First pregnancy: First-time mothers often deliver slightly later than the due date
- Multiple pregnancies: Twins and multiples typically arrive earlier
- Ultrasound dating: Early ultrasounds (before 13 weeks) provide the most accurate due date
When Will Labor Actually Start?
Most babies are born between 37 and 42 weeks of pregnancy. Only 5% arrive on their exact due date. About 70% of babies are born within 10 days of the due date (5 days before or after). First-time mothers are more likely to go past their due date, while subsequent pregnancies often deliver earlier.
Important Pregnancy Milestones
- Week 8-12: First prenatal visit and dating ultrasound
- Week 11-14: First trimester screening and nuchal translucency scan
- Week 18-22: Anatomy scan (20-week ultrasound)
- Week 24-28: Glucose screening test for gestational diabetes
- Week 35-37: Group B strep test
- Week 36+: Weekly prenatal visits until delivery
Frequently Asked Questions
How accurate is the due date calculator?
Due date calculators provide an estimate based on standard pregnancy length (40 weeks from LMP). Only about 5% of babies are born on their exact due date. Most babies arrive within 2 weeks before or after the estimated date. Early ultrasounds (before 13 weeks) provide the most accurate dating.
What if I don't remember my last period?
If you don't remember your last menstrual period, your healthcare provider will use an early ultrasound to date your pregnancy. Ultrasounds performed before 13 weeks are very accurate for determining gestational age and due date. You can also use the conception date method if you know when conception occurred.
Can my due date change?
Yes, your due date may be adjusted based on early ultrasound measurements. If there's a significant difference (more than 5-7 days) between the LMP-based date and ultrasound measurements, your provider will typically use the ultrasound date. After 20 weeks, due dates are rarely changed unless there's a clear error.
What happens if I go past my due date?
Going past your due date is common, especially for first-time mothers. Most providers will monitor you closely and may recommend induction between 41-42 weeks to reduce risks. You'll have more frequent check-ups and may have tests to monitor baby's well-being, such as non-stress tests and amniotic fluid checks.
Is 40 weeks really 9 months?
Pregnancy is actually about 9 months and 1 week. 40 weeks equals 280 days, which is approximately 9.3 months. The confusion comes from counting months as 4 weeks each, but most months have more than 28 days. Healthcare providers track pregnancy in weeks for more precision.
What's the difference between gestational age and fetal age?
Gestational age is calculated from the first day of your last menstrual period and is what healthcare providers use. Fetal age (or conceptional age) is calculated from conception, which typically occurs about 2 weeks after your LMP. Gestational age is about 2 weeks more than fetal age.
đ§ Guided Journeys
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These grouped paths are designed to help you continue with the most common follow-up calculations in this category.
Pregnancy Planning
Move from due dates to ovulation timing and pregnancy weight goals using one focused planning flow.
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