Pregnancy Due Date Calculator — Free Online Health Calculator | No Signup
This calculator provides an estimate and does not replace advice from a qualified healthcare professional.
Estimated due date
--Estimated conception date
--Current estimate
--Trimester
--Maintained and tested by Ivan Daniel · Methodology
Runs in your browser — No upload — runs entirely in your browser · Output: Calculated estimate, shown on the page
Educational estimate, not medical advice or a diagnosis. General formulas may not fit every individual — consult a qualified professional for medical decisions. See Methodology for the formula and assumptions.
Our Pregnancy Due Date Calculator estimates your baby's arrival date using Naegele's Rule — the standard method used by healthcare providers worldwide. Enter your last menstrual period date and get an instant estimated due date, current pregnancy week, and key milestones.
How to Use the Pregnancy Due Date Calculator
- Enter your LMP: Select the first day of your last menstrual period.
- Adjust cycle length: Default is 28 days — change if your cycle is shorter or longer.
- Read your results: Estimated due date, current week, trimester, and days remaining appear instantly.
How We Calculate Your Due Date
We use Naegele's Rule: EDD = LMP + 280 days (40 weeks). If your cycle differs from 28 days, we adjust accordingly: EDD = LMP + 280 + (cycle length - 28) days.
| Trimester | Weeks | General timeline |
|---|---|---|
| First | 1-12 | Early development and initial prenatal care planning |
| Second | 13-26 | Ongoing monitoring and routine appointments |
| Third | 27-40 | Continued care and birth preparation |
Frequently Asked Questions
How does this calculator estimate a due date?
It starts with the first day of the last menstrual period, adds 280 days, and adjusts by the average cycle length compared with a 28-day cycle. This calculator provides an estimate and does not replace advice from a qualified healthcare professional.
Why does cycle length change the estimate?
Cycle length can shift the estimated ovulation window. A longer cycle generally moves the estimated due date later, while a shorter cycle generally moves it earlier.
Is this result a medical diagnosis?
No. The result is an informational estimate only. A qualified healthcare professional can provide pregnancy dating using clinical history, examination, and ultrasound when appropriate.
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This calculator provides an estimate and does not replace advice from a qualified healthcare professional.