Health
Due Date Calculator
Estimate pregnancy due date from last menstrual period or conception date, and view current week, day, and trimester.
Due Date Calculator
Estimate due date based on last menstrual period or conception date, and see the current week and trimester.
This calculator gives a general estimate only and does not replace professional medical guidance, prenatal care, or ultrasound dating.
Direct answer
February 10, 2027
Estimated due date based on the selected method.
Current pregnancy week
Week 1
Current day in week
Day 0
Trimester
First trimester
Estimated due date
February 10, 2027
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How this due date calculator works
When you enter the first day of your last menstrual period, the calculator estimates due date by adding 280 days, which is the standard 40-week pregnancy length.
If you use conception date instead, the calculator estimates due date by adding 266 days.
This is a general estimate and does not replace professional medical guidance or ultrasound dating.
Formula notes
Standard due date estimates often use either:
- LMP + 280 days
- Conception date + 266 days
The current pregnancy week is estimated from the pregnancy start date relative to today.
What is a pregnancy due date calculator?
A pregnancy due date calculator estimates when a baby may be born based on the first day of the last menstrual period or a known conception date. It is a quick way to estimate due date, current pregnancy week, current day in week, and trimester stage.
Many people search for a due date calculator when they want to know how far along they are, when their expected delivery date may be, or how pregnancy timing changes across the three trimesters.
How to calculate your due date
The most common way to estimate a pregnancy due date is by using the first day of the last menstrual period. In a standard pregnancy, this estimate is calculated by adding 280 days, or 40 weeks, to the LMP date.
If the conception date is known, a due date can also be estimated by adding 266 days. This is often used when conception timing is more certain than cycle timing.
A due date calculator gives a useful estimate, but pregnancy timing can vary from person to person. Healthcare providers may refine the estimated due date using ultrasound and medical evaluation.
LMP due date vs conception date due date
The table below compares the two most common due date calculation methods.
| Method | Formula | Best used when |
|---|---|---|
| Last menstrual period (LMP) | LMP date + 280 days | People who know the first day of their last period but do not know the exact conception date. |
| Conception date | Conception date + 266 days | People who know conception timing more precisely, such as carefully tracked cycles. |
Pregnancy trimester chart and week ranges
| Trimester | Typical week range | Overview |
|---|---|---|
| First trimester | Weeks 1–13 | Early pregnancy development and initial body changes. |
| Second trimester | Weeks 14–27 | Often a more stable period with continued fetal growth. |
| Third trimester | Weeks 28–40 | Later pregnancy stage leading up to delivery. |
Pregnancy due date summary table
| Timeline item | Current estimate |
|---|---|
| Estimated pregnancy start | Based on last menstrual period |
| Current pregnancy week | Week 1, Day 0 |
| Current trimester | First trimester |
| Estimated due date | February 10, 2027 |
How many weeks pregnant am I?
Many users searching for a due date calculator are really asking how many weeks pregnant they are. Pregnancy is usually counted from the first day of the last menstrual period, not from the day conception occurred.
That means pregnancy week numbers often look about two weeks ahead of conception timing in a typical cycle. A due date calculator helps estimate the current week, current day, and trimester based on the selected method.
Why a due date can change
A due date may change if ultrasound measurements, cycle history, or clinical evaluation suggest a different pregnancy timeline. This is especially common when cycle length is irregular or the LMP date is uncertain.
Early ultrasound dating can sometimes provide a more useful estimate for clinical care. Always follow the guidance of a qualified healthcare provider for pregnancy dating and prenatal decisions.
Pregnancy due date calculator FAQ and common questions
How accurate is a due date calculator?
A due date calculator gives a general estimate. It is helpful for planning and reference, but the actual delivery date may differ.
Is the due date exact?
No. It is an estimate. Many pregnancies do not end exactly on the calculated due date.
Which is more accurate, LMP or conception date?
Conception date can be more precise if known accurately, but many people use last menstrual period because conception date is often uncertain.
Can ultrasound change the due date?
Yes. Healthcare providers may adjust estimated due date based on ultrasound findings, especially early in pregnancy.
Can my due date change during pregnancy?
Yes. A healthcare provider may adjust the estimated due date based on ultrasound findings, especially early in pregnancy.
Is 40 weeks always exact?
No. Forty weeks is the standard estimate used for due date calculation, but many pregnancies do not end exactly at 40 weeks.
Why does pregnancy dating use the last menstrual period?
LMP is often used because it is easier to identify than the exact date of conception and is a standard reference point in pregnancy dating.
Should I rely only on an online due date calculator?
No. It is useful for an estimate, but medical guidance and ultrasound dating are important for pregnancy care and more accurate clinical timing.
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