Estimate your pregnancy due date using multiple methods — last menstrual period (LMP), conception date, or IVF transfer date. Track your pregnancy week by week and learn about each trimester.
Understanding the three trimesters of pregnancy and what to expect during each stage.
The most common method for calculating due dates. Add 280 days (40 weeks) to the first day of your last menstrual period. This assumes a regular 28-day cycle and ovulation on day 14. The formula: LMP + 1 year - 3 months + 7 days.
If you know the exact date of conception (when the egg was fertilized), add 266 days (38 weeks) to that date. This is more accurate than the LMP method if you tracked ovulation with testing or monitored fertility treatments.
For IVF pregnancies, the due date depends on the embryo transfer day. For a Day 3 (cleavage stage) transfer, add 263 days. For a Day 5 (blastocyst) transfer, add 261 days from the transfer date.
First-trimester ultrasound (between weeks 8-14) provides the most accurate due date estimate. Crown-rump length (CRL) measurements can predict gestational age within 5-7 days. Later ultrasounds are less reliable for dating.
This formula assumes a 28-day menstrual cycle with ovulation on day 14. If your cycle is longer or shorter, the due date is adjusted accordingly.
Focus on folic acid (400-800 mcg daily), iron-rich foods, and adequate hydration. Avoid alcohol, raw fish, unpasteurized dairy, and limit caffeine to under 200mg daily. Small, frequent meals can help with morning sickness.
Moderate exercise like walking, swimming, and prenatal yoga is safe and beneficial. Aim for 30 minutes most days. Avoid high-impact activities, contact sports, and exercises that involve lying flat on your back after the first trimester.
Sleep on your left side to improve circulation, use pillows for support, and practice pelvic tilts to relieve back pain. Watch for signs of preterm labor including regular contractions, back pain, and pelvic pressure before 37 weeks.
Standard prenatal visits: monthly until week 28, every 2 weeks from weeks 28-36, and weekly from week 36 to delivery. Key screenings include glucose tolerance test (24-28 weeks), anatomy scan (18-22 weeks), and Group B Strep test (36-37 weeks).
Pregnancy can be emotionally challenging. Practice mindfulness, join a prenatal support group, and communicate openly with your partner and healthcare provider. Postpartum depression affects 1 in 7 women — knowing the signs helps early intervention.
By week 36, have your hospital bag packed, birth plan discussed with your provider, and childcare arrangements made if you have other children. Attend childbirth education classes and consider taking a newborn care or breastfeeding class.
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Naegele's Rule is the standard method healthcare providers use to estimate a due date. Named after German obstetrician Franz Naegele (1778-1851), the rule states: subtract 3 months from the first day of your last menstrual period (LMP), add 7 days, then add 1 year. For example, if your LMP was June 1, 2025, subtract 3 months to get March 1, 2025, add 7 days to get March 8, 2025, then add 1 year to get March 8, 2026 — your estimated due date. This accounts for the typical 280-day (40-week) duration of pregnancy from the LMP. The rule assumes ovulation occurs on day 14 of a 28-day cycle.
If your menstrual cycle is longer or shorter than 28 days, the due date should be adjusted. For each day your cycle is longer than 28 days, add one day to the due date. For each day shorter, subtract one day. For example, if your cycle is 32 days (4 days longer), your due date would be 4 days later than the standard calculation. This is because ovulation (and thus conception) occurs later in a longer cycle. Our calculator automatically applies this adjustment.
It's important to understand that only about 4% of babies are born exactly on their due date. A full-term pregnancy ranges from 37 to 42 weeks. Only about 70% of women deliver within 10 days of their due date. The due date is best thought of as a target date rather than a precise prediction. Factors like cycle irregularity, timing of ovulation, and individual variation all affect when labor naturally begins. Use your due date as a guide for planning, but expect some flexibility.
Our Due Date Calculator is a comprehensive tool designed to help expectant parents estimate their baby's due date using multiple proven methods. Whether you know your LMP, conception date, or are using IVF, our calculator provides accurate results based on standardized medical formulas used by healthcare providers worldwide.
Supports LMP, conception date, and IVF transfer date calculations. Also adjusts for cycle length to improve accuracy for non-28-day cycles.
See current pregnancy week, trimester, days remaining, and percentage complete. Also view key milestones like viability and full-term dates.
Uses Naegele's Rule and ACOG guidelines — the same formulas used by obstetricians and midwives worldwide for pregnancy dating.
All calculations are performed in your browser. No personal information is stored, transmitted, or shared with any third parties.
Learn about Naegele's Rule, trimester milestones, and factors that affect due dates with our comprehensive guides and FAQ.
Complete access to all features with no registration, no hidden fees, and no usage limits. Use it as often as you need.
Important Disclaimer: This Due Date Calculator provides estimates based on standard medical formulas and should not be considered medical advice. Due dates are estimates — only about 4% of babies are born exactly on their due date. Always consult with a qualified healthcare provider for pregnancy care, due date confirmation, and medical decisions. This tool is for informational and educational purposes only.