How to use this calculator
Choose Last period (LMP) or Conception date, enter the date in English or Nepali (BS), and — if you know it — set your average cycle length. You’ll see your due date in both calendars, how many weeks along you are, your trimester, and days to go.
How the due date is worked out
This uses Naegele’s rule: due date = first day of last period + 280 days (40 weeks). From conception it is + 266 days (38 weeks). The classic manual version is “take the first day of your last period, add 7 days, subtract 3 months, add 1 year.” If your cycle isn’t 28 days, the estimate is shifted by the difference (e.g. a 32-day cycle adds ~4 days).
Trimesters and key weeks
| Trimester | Weeks |
|---|---|
| First | Up to 13 weeks 6 days |
| Second | 14 – 27 weeks 6 days |
| Third | 28 weeks to birth |
| Full term | 37 – 42 weeks |
Antenatal (ANC) care in Nepal
Nepal’s safe-motherhood programme recommends at least four (now eight) antenatal check-ups, iron-folic acid tablets, TT/Td vaccination and an early dating ultrasound. Free ANC and delivery (and the Aama Surakshya transport incentive) are available at government health facilities. Use this due date to plan your check-up schedule with your health worker — it does not replace their advice.
Accuracy & disclaimer
This is an estimate, not a diagnosis. Babies rarely arrive exactly on the due date — most come within two weeks either side. A first-trimester ultrasound dates a pregnancy more accurately than period dates, particularly with irregular cycles. Always follow your doctor or midwife.
Tracking your cycle? See the private Period & Cycle Tracker, and convert any date with the Nepali Date Converter.
Frequently asked questions
How is the due date calculated?
By Naegele's rule: the estimated due date (EDD) is 280 days (40 weeks) after the first day of your last menstrual period (LMP). From the conception date it is 266 days (38 weeks). If your cycle is longer or shorter than 28 days, the LMP estimate is adjusted accordingly.
Can I enter the date in Nepali (Bikram Sambat)?
Yes. Switch the date input to Nepali (BS) and pick the Baisakh–Chaitra month, day and year. The due date is then shown in both English (AD) and Nepali (BS) dates so it's easy to note in either calendar.
How accurate is the due date?
It is an estimate. Only about 1 in 20 babies are born on the exact due date; most arrive within two weeks either side. A first-trimester dating ultrasound (crown-rump length) is more accurate than period dates, especially if your cycle is irregular. Your doctor may adjust the date after a scan.
What are the trimesters?
First trimester is up to 13 weeks 6 days, second trimester is 14 to 27 weeks 6 days, and third trimester is 28 weeks onward until birth. A pregnancy is considered full term from 37 weeks.
What if my periods are irregular or I don't know my LMP?
Use the conception date option if you know it, or get a dating ultrasound — that is the most reliable method when periods are irregular or unknown. Don't rely on LMP dating alone in that case.
Is my information private?
Yes. The calculation runs entirely in your browser. Your dates are never uploaded or stored on a server.