Pregnancy Due Date Calculator
Calculate your expected due date and pregnancy week.
Quick guide
How Due Date Is Estimated
This calculator uses Naegele's rule, a common clinical estimate based on the first day of your last menstrual period. In a typical 28-day cycle, due date is estimated by adding 280 days, or 40 weeks, to that start date.
If your cycle length differs from 28 days, the estimate shifts slightly so the due date better matches your cycle pattern. Even then, the result is still an estimate and should be treated as a planning tool rather than an exact delivery prediction.
Trimester Overview
- First trimester: early development and common symptom changes
- Second trimester: major growth phase and the period when many people feel more stable
- Third trimester: final growth, birth planning, and preparation for delivery
- Full term is usually considered around 37 weeks, but actual delivery timing varies widely
Example
If the first day of the last menstrual period is 18 March 2026 and the cycle length is close to 28 days, the calculator estimates a due date about 40 weeks later. The exact date can still move after ultrasound or clinical review.
Frequently Asked Questions
How accurate is the due date calculation?
Due dates are estimates, not guarantees. Many healthy pregnancies do not end on the exact date predicted by a calculator, so the result is best used as a planning reference and not a medical promise.
What if my cycle is not 28 days?
If your cycle is longer or shorter than 28 days, the estimated date can shift. Entering your typical cycle length gives a more useful estimate than assuming every cycle is identical.
What is the conception date?
Conception often occurs around ovulation, usually about two weeks after the first day of the last menstrual period in a 28-day cycle. The exact date can vary by a few days.
Quick answer
Pregnancy Due Date Calculator is built for people who want a fast, browser-based way to calculate your expected due date and pregnancy week. The tool works well for quick checks on mobile or desktop, and the supporting explanation helps you understand the result instead of treating it like a black box.
How to use this tool
- Fill in the required values carefully and keep the units or date formats consistent.
- Read the primary result first, then review the supporting breakdown to understand how the answer was produced.
- Change one input at a time if you want to compare scenarios and make a clearer decision.
How to interpret the result carefully
Health calculators are useful for direction, not diagnosis. They help you create a starting point, notice a trend, or understand a measurement, but they do not replace symptoms, lab work, medical history, or professional review.
That is why the number matters most when you combine it with context: how you feel, what your doctor has told you before, and whether the result is part of a pattern over time instead of a one-off reading.
When this result is useful
Use the result as a quick health or fitness reference when you want a clearer starting point for daily decisions.
It works best when paired with common sense, your medical history, and professional advice if symptoms, medication, or long-term conditions are involved.
A practical health check example
Someone tracking progress over a few weeks can use Pregnancy Due Date Calculator to create a clearer baseline instead of relying on guesswork.
The value becomes more useful when you compare it with daily habits such as food, sleep, hydration, movement, and recovery rather than treating the number as a final diagnosis on its own.
Common interpretation mistakes to avoid
- Treating one result as a diagnosis instead of a screening reference.
- Ignoring age, body composition, medical history, or medication context.
- Using a number once and never checking whether it changes over time.
- Skipping professional advice when symptoms or risks are already present.
Sources and notes
For informational use only. This tool is not medical advice and should not replace diagnosis, treatment, or individualized guidance from a qualified healthcare professional.