Pregnancy Due Date Calculator
Estimate your baby's due date using LMP, conception date, or IVF transfer date. See current gestational age, trimester dates, and key pregnancy milestones.
Calculation method:
How to use Pregnancy Due Date Calculator
The due date calculator estimates your expected delivery date (EDD) using four methods: last menstrual period (LMP) via Naegele's Rule, conception date, IVF 3-day embryo transfer or IVF 5-day blastocyst transfer. It also shows your current gestational age if you are already pregnant, trimester boundaries and six key prenatal milestones from the first prenatal visit to the 40-week mark.
- Select your calculation method: LMP (most common), conception date, or IVF transfer date.
- Enter the corresponding date using the date picker.
- Your estimated due date, gestational age and trimester information appear immediately.
- Review the milestone timeline for key prenatal dates.
Your data never leaves your device — 100% private processing.
Naegele's Rule and the 280-day standard
Naegele's Rule adds 280 days (40 weeks) to the first day of the last menstrual period, assuming a 28-day cycle with ovulation on day 14. Only about 4–5% of babies are born on their exact due date; most arrive within a two-week window on either side. The rule dates from 1812 but remains the worldwide clinical standard for dating pregnancies confirmed by ultrasound.
The three trimesters explained
Pregnancy is divided into three trimesters. The first trimester (weeks 1–12) covers implantation, organ formation and the highest risk of miscarriage. The second trimester (weeks 13–27) is typically the most comfortable, with anatomy scan around week 20. The third trimester (weeks 28–40) involves rapid fetal growth, lung maturation and preparation for birth. Premature birth is defined as delivery before 37 weeks.
Glossary
- EDD
- Estimated Due Date — the predicted date of delivery.
- Gestational age
- Pregnancy duration measured in weeks and days from the LMP.
- LMP
- Last Menstrual Period — the standard starting point for dating a pregnancy.
- IVF
- In vitro fertilisation — assisted reproduction where fertilisation occurs outside the body.
- Trimester
- One of three roughly equal stages of pregnancy, each approximately 13 weeks.
Related reading
Frequently Asked Questions
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Why use Pregnancy Due Date Calculator?
- Based on widely-accepted clinical and scientific formulas
- No personal data stored — all calculations run locally
- Supports both metric and imperial units
- Results include actionable recommendations
Common use cases
- Calculate BMI before a doctor's appointment
- Estimate daily calorie needs for a weight loss goal
- Track ideal body weight range for a fitness plan
- Calculate pregnancy due date
- Find out your recommended water intake based on body weight
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