Pregnancy Countdown Calculator — Days Until Due Date
Enter your last menstrual period (LMP) or known due date to see exactly how many days and weeks remain until your baby arrives, which trimester you are in, and how far through the 40-week journey you have come.
Input method
First day of last period (LMP)
Today's date
25 weeks 1 days remaining
How does this calculator work?
Subtract today from your due date (LMP + 280 days) to get days remaining; divide by 7 for weeks and days. Most pregnancies last 38–42 weeks; the 40-week (280-day) estimate is a statistical midpoint, not a precise expiry date.
Formula
How this is calculated
Pregnancy is conventionally dated from the first day of the last menstrual period (LMP) and lasts 280 days (40 weeks) according to Naegele's rule. The estimated due date is simply the LMP plus 280 calendar days. Subtracting today's date from the due date gives the number of days remaining; dividing by 7 converts this to whole weeks and extra days, which is how midwives and apps typically report the countdown.
If you already know your due date (for example from an ultrasound scan), you can enter it directly and the calculator works backwards. The gestational week and trimester shown are derived from the LMP when available, or estimated from the due date otherwise (40 weeks − weeks remaining). First trimester is weeks 1–13, second is weeks 14–27, and third is weeks 28 onward.
All dates are treated as midnight in the browser's local timezone. The progress percentage is the elapsed fraction of the 280-day term, clamped to 0–100%. Due dates are estimates — about 80% of babies arrive within two weeks either side of the predicted date — so treat the countdown as a guide rather than a fixed deadline.
Frequently asked questions
The due date is the first day of your last menstrual period plus 280 days (40 weeks). This is Naegele's rule and is the standard used by midwives and apps worldwide. It assumes a 28-day cycle with ovulation at day 14; for irregular cycles an early ultrasound may give a more accurate estimate.
A full-term singleton pregnancy is 40 weeks (280 days) from the LMP, though 39–40 weeks is considered "full term" and 37–38 weeks "early term". Births from 37 weeks onward are generally classified as term; before 37 weeks is preterm.
An ultrasound dating scan (usually at 8–12 weeks) is often more accurate than LMP dating because it measures the embryo directly and is unaffected by cycle length. Use the scan-based due date in the "Known due date" mode for the best accuracy.
Also known as
TG we-Calculate Editorial Team. (2026). Pregnancy Countdown Calculator — Days Until Due Date [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/pregnancy-countdown-calculator
TG we-Calculate Editorial Team. "Pregnancy Countdown Calculator — Days Until Due Date." TG we-Calculate. 2026. https://we-calculate.com/calculator/pregnancy-countdown-calculator.
TG we-Calculate Editorial Team, "Pregnancy Countdown Calculator — Days Until Due Date," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/pregnancy-countdown-calculator
@misc{wecalculate_pregnancy_countdown_calculator, title = {Pregnancy Countdown Calculator — Days Until Due Date}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/pregnancy-countdown-calculator}}, year = {2026}, note = {TG we-Calculate} }
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