Enter LMP date to estimate due date and see your trimester.
This is an estimate only — consult a healthcare professional for all prenatal care decisions.
This is an estimation tool only — your OB/GYN will establish your official due date using ultrasound dating. Always follow your healthcare provider's guidance for prenatal care.
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Estimate pregnancy due date from the first day of your last menstrual period (LMP) with a simple 40-week calculation. Runs locally in your browser when supported—no upload required for normal use. Designed for quick everyday tasks with clear, copy-friendly output.
Estimate pregnancy due date from the first day of your last menstrual period (LMP) with a simple 40-week calculation.
Common real-world scenarios where this tool saves time.
Estimate expected due date from LMP and see current pregnancy week using a standard 40-week method.
Use when you want results without uploading files—local browser processing when the tool supports it.
Open Pregnancy Due Date Calculator in any modern browser for quick checks with copy-friendly output.
Reference timeline of standard prenatal appointments and development milestones.
| Weeks | Milestone | Why It Matters |
|---|---|---|
| 4–6 | Pregnancy confirmed (home test / blood hCG) | Earliest detectable; begin prenatal vitamins |
| 8–10 | First OB appointment | Initial exam, blood work, and due date discussion |
| 11–14 | First-trimester ultrasound + NT scan | Nuchal translucency screening; chromosomal risk assessment |
| 16–18 | Quad screen / NIPT results | Genetic screening results |
| 18–20 | Anatomy scan (Level II ultrasound) | Major organ check; sex determination possible |
| 24–28 | Glucose tolerance test | Gestational diabetes screening |
| 35–37 | Group B Strep (GBS) test | Infection screening for birth |
| 39–40 | Estimated due date | Full term; birth expected ±2 weeks |
Schedule and timing may vary based on your provider's protocol and pregnancy risk factors.
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Using Naegele's rule: add 280 days (40 weeks) to the first day of your last menstrual period. Equivalently, add 9 months and 7 days to your LMP. This assumes a 28-day cycle with ovulation at day 14. Your healthcare provider will adjust this with early ultrasound dating.
Only about 4–5% of babies are born on their exact estimated due date. The LMP method is a planning estimate accurate to within ±2 weeks for most pregnancies. Ultrasound dating (especially before 12 weeks) is more accurate and may shift the due date by days to weeks if cycles are irregular.
First trimester: weeks 1–12 (implantation, major organ development, highest miscarriage risk). Second trimester: weeks 13–26 (rapid growth, gender visible, anatomy scan). Third trimester: weeks 27–40+ (lung maturation, weight gain, birth preparation). Full-term is 39–40 weeks; 37 weeks is considered early term.
40 weeks is the estimated due date. Most providers discuss induction options if no labor occurs by 41–42 weeks due to increased risks of placental aging. Approximately 80% of babies are born between weeks 37 and 42.
Yes. Early ultrasounds (before 12 weeks) are the most accurate dating tool and may revise the LMP-based EDD. If the ultrasound date differs by more than 7 days in the first trimester, or 14 days in the second trimester, the ultrasound date replaces the LMP date as the official EDD.
Gestational age counts from the first day of the LMP — so at conception (about day 14), you are already '2 weeks pregnant.' Fetal age (embryonic age) starts at conception and is typically 2 weeks less than gestational age. Medical providers use gestational age; it is what appears on your ultrasound report.
Yes. The standard calculation assumes ovulation at day 14 of a 28-day cycle. If your cycle is 35 days, ovulation likely occurs at day 21, making your due date 7 days later than the standard LMP calculation. Entering your actual cycle length in this calculator adjusts for this.
Early term: 37–38 weeks 6 days. Full term: 39–40 weeks 6 days. Late term: 41–41 weeks 6 days. Post-term: 42+ weeks. Full-term (39+ weeks) is associated with the best outcomes for most healthy pregnancies.
LMP dates and cycle length stay on your device—due-date math is not uploaded to EverydayTools servers.
Only about 4–5% of births occur on the exact EDD; clinical ultrasound dating in the first trimester is more precise than LMP alone.
Educational pregnancy dating estimate only—not medical advice. Confirm your due date and prenatal plan with your obstetrician or midwife.
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Reviewed by EverydayTools Editorial Team on 2026-06-02.
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Enter LMP date to estimate due date and see your trimester.
This is an estimate only — consult a healthcare professional for all prenatal care decisions.