Pregnancy Calculator
Enter your last menstrual period to estimate your due date, current week, and a personalized checkup timeline
Based on Naegele's rule (LMP + 280 days) and the standard prenatal care checkpoints, we generate a personalized pregnancy timeline along with a detailed guide covering fetal development, maternal changes, nutrition, and prenatal education for your current week.
Last menstrual period date
🍒 Your baby is about the size of a cherry
Days until due date 219
Due date Jun 12, 2027 · 61 days pregnant
Prenatal checkup timeline (based on your LMP)
The timeline follows the standard checkup nodes recommended by prenatal care guidelines, with dates converted from your entered last menstrual period to help you book in advance.
Baby's star sign & zodiac prediction
Based on the estimated due date of Jun 12, 2027, your baby's sun sign would likely be Gemini, with a Chinese zodiac animal of Goat. Actual birth dates can drift from the estimate, so the star sign and animal should be based on the real date of birth (the Chinese zodiac animal also follows the lunar year of birth).
How the pregnancy calculator works — Naegele's rule
This calculator uses Naegele's rule: starting from the first day of the last menstrual period (LMP), add 280 days (40 weeks) to estimate the due date, and the current week = days since the LMP ÷ 7. Pregnancy is divided into the first trimester (weeks 1–13), second trimester (weeks 14–27), and third trimester (week 28+).
The algorithm assumes a 28-day cycle with ovulation on day 14. If your actual cycle is longer or shorter, results may differ due to individual variation. Your doctor may further adjust the due date using an early ultrasound.
Estimating the due date by conception date, IVF, or irregular cycles
By conception (intercourse) date: if you know the approximate conception date, add 266 days (38 weeks) to estimate the due date. This is equivalent to LMP + 280 days, since conception typically happens about 14 days after the LMP. It is useful when your cycle is irregular but ovulation timing is clear.
By IVF/IUI: embryo transfer dates are precise, so the estimate is more accurate — use the egg retrieval date (≈ conception) + 266 days; or by transfer day, +263 days for a day-3 embryo and +261 days for a day-5 blastocyst. For IUI, add 266 days from the insemination date.
Irregular periods: a longer cycle usually means the LMP-based weeks are an underestimate. In this case, an early ultrasound (especially at 7–13 weeks) measuring the crown–rump length is more reliable for dating, and your doctor will adjust the due date accordingly.
What to focus on in each trimester
First trimester (weeks 1–13): a critical stage for fetal organ development. Take folic acid, avoid alcohol, tobacco, and harmful environments, and complete your prenatal records within weeks 8–12. Seek care for abdominal pain or bleeding.
Second trimester (weeks 14–27): your baby grows quickly. Eat a balanced diet and exercise moderately. Most mothers feel fetal movement here — a great time to bond. Do not skip the second-trimester screening and anatomy scan.
Third trimester (week 28+): watch fetal movement, weight, and blood pressure closely. From week 34, attend weekly heart-rate monitoring and prepare your hospital bag. Go straight to the hospital for regular contractions (every 5–10 minutes), ruptured membranes, or bleeding.
Track weight changes with the pregnancy weight-gain guide and record checkup dates with the reminder notes tool.
Pregnancy calculator FAQ
Q：What can this pregnancy calculator do?
A：From your last menstrual period date, it estimates the due date, current week, trimester, progress percentage, and days until the due date, and automatically builds a personalized prenatal schedule plus a star-sign and Chinese-zodiac prediction for your baby. Great for planning your pregnancy timeline and checkup calendar.
Q：How is the due date calculated?
A：We use the commonly used Naegele's rule: add 280 days (40 weeks) to the first day of the LMP. Current week = days since the LMP ÷ 7. This is the same LMP-based principle described in ACOG's Methods for Estimating the Due Date.
Q：Is the due date exact?
A：No due date is exact. Based on Naegele's rule, delivering within 2 weeks either side of the estimate (weeks 38–42) is considered normal, and only about 5% of babies arrive on their exact due date. Actual dates vary by individual, and doctors refine the estimate with ultrasound.
Q：What if the due date passes?
A：Not going into labor by week 40 is common, and weeks 41–42 are still within the observable range. Doctors typically increase monitoring (heart-rate tests and ultrasound of fluid and placenta) and decide whether induction is needed. Follow your obstetrician’s plan and seek immediate care if fetal movement drops, your water breaks, or you have regular contractions or bleeding.
Q：How do I date the pregnancy with irregular cycles?
A：Naegele's rule assumes a 28-day cycle with ovulation on day 14. With longer or shorter cycles, the LMP-based estimate drifts — the longer the cycle, the more the true gestational weeks exceed the estimate. In this case, use an early ultrasound (especially at 7–13 weeks) measuring crown–rump length, which is more accurate than the LMP estimate.
Q：How do I estimate the due date from the conception date?
A：If you know an accurate conception date, add 266 days (38 weeks). This is equivalent to LMP + 280 days because conception usually occurs about 14 days after the LMP. It works well when your cycle is irregular but ovulation/conception timing is known.
Q：How is the due date calculated for IVF?
A：Because the embryo transfer date is precise, the estimate is more accurate: for fresh or frozen transfer use the egg-retrieval date (≈ conception) + 266 days; or by transfer day, +263 days for a day-3 embryo and +261 days for a day-5 blastocyst. For IUI, add 266 days from the insemination date.
Q：Is the prenatal checkup schedule accurate?
A：The schedule is derived from your LMP and the standard checkpoints in prenatal care guidelines (NT, trisomy screening, anatomy scan, glucose tolerance, heart-rate monitoring, etc.), which is useful for planning. Your doctor decides the exact timing.
Q：Is the LMP-based due date reliable?
A：It is the most common dating method and a good quick reference. If your cycle is irregular or ovulation timing is unusual, results may vary, so combine it with an ultrasound assessment.
Q：How do I know how many weeks pregnant I am?
A：Gestational age is counted from the first day of the LMP (not conception), so about 2 weeks are counted before conception. Enter your LMP and this tool converts it into the current week and day; if your cycle is irregular, follow the ultrasound-confirmed estimate.
Q：Does this page provide medical diagnosis?
A：No. This tool provides algorithm-based estimates of gestational age, due date, and checkup timing to help you plan. Medical diagnosis and individualized advice require consultation with an obstetrician.
Q：What is the due date?
A：The expected date of delivery (EDD) is the estimated birth date based on the LMP or conception date. Medicine uses 40 weeks (280 days) as a full term, but only about 5% of babies are born on the exact estimate; delivery within 2 weeks either side (weeks 38–42) is normal.
Q：What if I don't remember the LMP?
A：Try recalling nearby milestones (holidays, trips) or using early-pregnancy symptoms (usually around week 6) to work backward. The most reliable method is an early ultrasound (7–13 weeks) measuring crown–rump length; doctors usually adjust the due date from the early scan.
Q：Ultrasound and LMP give different due dates — which wins?
A：If they differ by a week (7 days) or less, the LMP estimate is usually kept. If they differ by more than a week (especially early on), the early ultrasound fetal size is usually preferred, since early dating scans are more accurate than recalled LMP. Follow your doctor's overall judgment.
Q：How is the due date estimated for twins?
A：The formula is the same as for a singleton (LMP + 280 days), but twins often deliver early — most dichorionic or monochorionic twins are born around weeks 37–38. Doctors decide timing based on fetal development and maternal condition.
Q：What is the difference between the conception-date and LMP modes?
A：They are essentially equivalent: the LMP mode adds 280 days from the first day of the LMP assuming ovulation on day 14; the conception mode adds 266 days (38 weeks), since conception usually occurs about 14 days after the LMP. Use the conception mode when you know a reliable conception date (e.g., ovulation tracking, clear intercourse timing, or IVF); use the LMP mode when your cycle is regular and you remember the LMP.
Data sources & notes
- Guidelines for Pre-conception and Prenatal Care (Chinese Society of Obstetrics and Gynecology)
- ACOG Methods for Estimating the Due Date (Committee Opinion No.700)
- WHO INTERGROWTH-21st fetal growth standards
This tool provides algorithm-based estimates from the authoritative standards above for pregnancy time planning and general reference. It does not replace a doctor's diagnosis or individualized medical advice; follow your obstetrician for all prenatal care decisions.