Calculate your estimated due date based on last period or conception date.
Quick answer
With a 28-day cycle the estimated due date is October 8, 2026, which is 280 days (40 weeks) after the first day of the last period. Only about 4% of babies are born on their due date, and most arrive within two weeks either side.
| Cycle length | Estimated due date |
|---|---|
| 24 days | October 4, 2026 |
| 26 days | October 6, 2026 |
| 28 days | October 8, 2026 |
| 30 days | October 10, 2026 |
| 32 days | October 12, 2026 |
| 35 days | October 15, 2026 |
These figures are computed with the same formulas as the Pregnancy Due Date Calculator above. Change the inputs in the tool to see your own result.
The Pregnancy Due Date Calculator estimates your due date from the first day of your last menstrual period (adjusted for your cycle length) or from a known conception date. It also shows how many weeks and days pregnant you are today, the trimester and the likely date of conception. It uses the standard 40-week method and runs in your browser. It is an estimate, and your healthcare provider's dating is the one to follow.
Made for everyone. Typical uses:
If the first day of your last period was 1 January 2026 and your cycle is 28 days, the estimated due date is Thursday 8 October 2026. With a 32-day cycle it moves to Monday 12 October. A conception date of 5 October 2026 gives a due date of Monday 28 June 2027.
It uses Naegele's rule, adjusted for the cycle length, so it cannot account for irregular cycles or an uncertain date and can differ by a week or more from an ultrasound-based date. The trimester boundaries are conventions (the first trimester is counted to 14 weeks here). It is not medical advice.
Accuracy: Formulas follow standard published methods and are checked against worked reference examples. Results are estimates based on the values you enter and do not replace advice from a qualified professional.
Expert Tip
If your cycle is regularly longer or shorter than 28 days, treat the calculated date as a rough starting point and rely on your provider's early ultrasound for a more accurate due date, since ultrasound dating adjusts for actual fetal size.
The Pregnancy Due Date Calculator estimates when a baby is due and how far along the pregnancy is today. Choose "Last period" and enter the first day of your last menstrual period and your average cycle length, or choose "Conception date" if you know it, for example after fertility treatment. The tool shows the estimated due date, the current week and day of pregnancy, the trimester and the likely date of conception.
From the last period, the tool uses Naegele's rule: the due date is 280 days, or 40 weeks, after the first day of the last period. That assumes a 28-day cycle with ovulation around day 14, so for a longer or shorter cycle the tool shifts the date by the difference. If your cycle is 32 days, the date moves four days later. From a conception date, the due date is 266 days later, which is 38 weeks. Pregnancy is counted in gestational weeks from the last period, so a pregnancy is already about two weeks along on the day of conception.
These dates come directly from the calculator.
This calculator counts the first trimester up to 14 weeks, the second from 14 to 28 weeks and the third from 28 weeks until birth. Some sources end the first trimester at 12 or 13 weeks, so you may see slightly different dates elsewhere. The boundary is a convention and does not mark a change in anything medical.
A due date is a midpoint, not a deadline. Only about 4 percent of babies arrive on the estimated date, and most arrive within two weeks either side. A birth between 39 weeks and 40 weeks 6 days is usually called full term. If your periods are irregular, you are unsure of the date, or you conceived while using hormonal contraception, the calculation can be out by a week or more, and an early ultrasound gives a more accurate estimate. Doctors and midwives sometimes revise the due date after a dating scan.
Use the date to plan appointments, leave from work and time off. To count days between two dates, such as the weeks until a planned leave, use the Days Between Dates calculator, and the Age Calculator shows how old a child will be on a given day. During pregnancy, the BMI Calculator and Calorie Calculator are not designed for it, because their formulas assume you are not pregnant. This tool is not medical advice, and your healthcare provider's dating is the one to follow. Dates are processed in your browser and are not stored.
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