Health
Pregnancy Calculator | Due Date, Week and Trimester
Estimate your due date, current pregnancy week, trimester, and milestone dates from last menstrual period (LMP) or estimated due date.
Pregnancy Calculator
Estimate current pregnancy week, trimester, due date, and key milestone dates from last menstrual period or due date.
Direct answer
Week 1
Day 0 • First trimester
Estimated due date
29 April 2027
Pregnancy start date
23 July 2026
Trimester
First trimester
Save and export multiple pregnancy results
Save pregnancy week, due date, trimester, and milestone results, then export selected rows as a CSV or TXT file.
Page guide
On this page
Jump to the due date formula, pregnancy timeline, trimester chart, milestone dates, or FAQ.
Pregnancy timeline
Milestones
How it works
LMP and due date
Formula notes
280-day model
What is a pregnancy calculator?
Definition
Calculate pregnancy week
LMP and due date
Trimester chart
Weeks by trimester
Common pregnancy weeks
Popular milestones
Interpret results
Week and due date
LMP vs due date
Calculation methods
Pregnancy FAQ
Common questions
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Pregnancy milestone timeline
| Milestone | Estimated date |
|---|---|
| Second trimester begins | 22 October 2026 |
| Third trimester begins | 28 January 2027 |
| Full term (37 weeks) | 8 April 2027 |
| Estimated due date | 29 April 2027 |
How this pregnancy calculator works
This calculator estimates pregnancy progress from either last menstrual period or an estimated due date.
It calculates the current pregnancy week, trimester, estimated due date, and several common milestone dates.
This is an informational estimate and does not replace professional prenatal care or ultrasound dating.
Formula notes
Standard pregnancy timing usually uses a 40-week model counted from the last menstrual period.
Pregnancy timing idea
Estimated due date = Pregnancy start + 280 days
What is a pregnancy calculator?
A pregnancy calculator is a tool that estimates how far along a pregnancy is based on either the first day of the last menstrual period or an estimated due date. It helps answer common questions such as how many weeks pregnant you are, which trimester you are in, and when major pregnancy milestones may happen.
Many people search for a due date calculator or pregnancy week calculator when they want a quick estimate before a medical appointment. This tool is designed to provide that estimate in a simple format with current week, trimester, due date, and milestone dates all in one place.
How to calculate pregnancy week and due date
Standard pregnancy dating usually uses a 40-week model counted from the first day of the last menstrual period. In that model, the estimated due date is often calculated as 280 days after the pregnancy start date.
This is why pregnancy weeks are usually counted a little earlier than actual conception. If you already know your estimated due date, the calculator can work backward to estimate your current pregnancy week and trimester.
This approach is useful for general tracking, planning, and reference. However, ultrasound dating and clinical guidance may lead to a more accurate pregnancy timeline.
Pregnancy trimester chart by week
| Trimester | Typical weeks | General stage |
|---|---|---|
| First trimester | Weeks 1–13 | Early pregnancy and foundational fetal development |
| Second trimester | Weeks 14–27 | Mid-pregnancy growth and anatomical development |
| Third trimester | Weeks 28–40 | Late pregnancy growth, positioning, and birth preparation |
Common pregnancy weeks people look up
| Pregnancy week | Common reason people check |
|---|---|
| Week 4 | Missed period and early pregnancy testing |
| Week 6 | Early symptom tracking and first appointment planning |
| Week 8 | Common timing for first prenatal check |
| Week 12 | End of first trimester for many pregnancies |
| Week 20 | Mid-pregnancy milestone and anatomy scan timing |
| Week 28 | Start of third trimester |
| Week 37 | Early term stage and birth preparation |
| Week 40 | Estimated due date period |
What your pregnancy calculator result means
Your current pregnancy week shows how far along the pregnancy is based on the selected method. The trimester label helps group the pregnancy into broader stages that many people use for planning and tracking.
The estimated due date is not a guarantee of delivery on that exact day. Instead, it is a reference point used for prenatal scheduling, milestone planning, and general pregnancy progress tracking.
The milestone timeline is useful for quickly seeing key stages in a 40-week pregnancy model. It can help with appointment planning, personal tracking, and understanding where you are in the overall pregnancy timeline.
When to use an LMP pregnancy calculator vs due date method
Use the last menstrual period method when you know the first day of your most recent period and want to estimate your pregnancy week and due date from that starting point.
Use the due date method when a healthcare provider has already given you an estimated due date or when you want to check what pregnancy week lines up with that date.
Both methods are helpful for general reference, but medical dating may be adjusted later based on ultrasound findings or clinical assessment.
Pregnancy calculator FAQ: due date, pregnancy weeks, and trimesters
How is a pregnancy due date calculated?
A pregnancy due date is commonly estimated as 280 days, or 40 weeks, from the first day of the last menstrual period. This is a standard pregnancy dating method used for planning and reference.
How many weeks pregnant am I based on my last menstrual period?
Pregnancy weeks are usually counted from the first day of the last menstrual period, not from conception. That is why pregnancy age is often about two weeks ahead of fetal age.
What trimester am I in by week?
The first trimester is generally weeks 1 to 13, the second trimester is weeks 14 to 27, and the third trimester is weeks 28 to 40.
Is pregnancy week the same as fetal age?
No. Pregnancy week is usually counted from the last menstrual period, which is typically about two weeks before conception.
Can due date estimates change after an ultrasound?
Yes. Healthcare providers may revise the estimated due date based on ultrasound measurements or updated clinical information.
Is this pregnancy calculator a medical tool?
No. It is a planning and reference tool, not a substitute for medical advice, prenatal care, or ultrasound dating.
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