Pregnancy Calculator
Pregnancy Calculator: Calculate Your Due Date, Pregnancy Week & Baby Milestones
A pregnancy calculator is an easy online tool that helps expecting mothers estimate their due date, current pregnancy week, trimester stage and overall pregnancy timeline. It uses either your last menstrual period (LMP) or your conception date to give pregnancy estimates and milestones.
Our free pregnancy calculator gives fast results for tracking your pregnancy week by week. Whether you are newly pregnant or already in your second or third trimester, it helps you understand your baby’s development timeline and how many weeks remain until delivery. It shows your estimated due date, current pregnancy week, time left until delivery, current trimester, days pregnant, a milestone for this week, weekly tips and the zodiac sign of your due date.
Quick answer: if your last period started on June 1, 2026, your estimated due date is March 8, 2027. If you know you conceived on June 15, 2026, the due date is March 8, 2027. Choose a method above and enter your own date to see how many weeks pregnant you are today.
What Is Pregnancy Calculation?
Pregnancy calculation is the process of estimating how far a pregnancy has progressed and predicting the expected delivery date. Doctors and pregnancy tracking tools commonly use two methods:
| Method | How the due date is found | Best used when |
|---|---|---|
| LMP (Naegele’s Rule) | First day of last period + 280 days (40 weeks) | You know your last period date and have a regular cycle of about 28 days |
| Conception date | Conception date + 266 days (38 weeks) | You know the exact conception date, such as from ovulation tracking |
The LMP method is the most common medical method because many women do not know the exact conception date. It follows Naegele’s Rule, which adds 280 days, or 40 weeks, to the first day of your last menstrual period. Because pregnancy is counted from the last period, you are already about two weeks pregnant on the day of conception. Pregnancy calculation also gives you your gestational age, trimester, fetal growth timeline and an approximate delivery period. Doctors often compare ultrasound scans with these calculations to monitor development. For ultrasound and IVF dating, or an adjustment for a longer or shorter cycle, use the due date calculator.
Pregnancy Trimesters Explained
Pregnancy is divided into three trimesters. The calculator shows which one you are in and highlights it in the progress bar.
| Trimester | Weeks | What to expect |
|---|---|---|
| First | Weeks 1–13 | Major organs form; morning sickness, fatigue and hormonal changes are common |
| Second | Weeks 14–27 | Often the most comfortable phase; baby movements become noticeable and growth is rapid |
| Third | Weeks 28–40 | Rapid growth and preparation for birth; hospital bag, birth plan and newborn essentials |
The calculator shows your gestational age in weeks and days. Someone who is 6 weeks and 3 days pregnant has completed 6 weeks and is in week 7, which is why the Current Week box shows one more than the number of completed weeks.
Pregnancy Calculator Accuracy
Pregnancy calculators provide estimated due dates based on the average pregnancy length. Actual delivery dates vary because every pregnancy is different. Only a small percentage of babies are born exactly on their due date, and most births occur between weeks 38 and 42. If your periods are irregular, the estimate may be less accurate, and an ultrasound can give a more precise date. For medical accuracy and prenatal care, always consult a healthcare professional. The tips and milestones shown here are general information and not medical advice.
Who Uses a Pregnancy Calculator?
Expecting mothers use it to track progress, estimate due dates and follow weekly baby development. Couples planning for a baby use it to understand conception timelines, and the period calculator can help with fertility tracking before pregnancy. Healthcare professionals such as doctors, nurses and midwives use pregnancy calculations as a basic reference during prenatal care. Family members use due dates to prepare for childbirth, baby showers and delivery plans, and parenting bloggers use them to help readers.
Why Use an Online Pregnancy Calculator?
An online pregnancy calculator gives you a quick due date estimate, easy pregnancy tracking, a better understanding of the trimesters, weekly progress updates, helpful prenatal reminders, free and instant results, and mobile-friendly access. Your dates are calculated in your browser, and nothing is saved or sent anywhere.
How to Use This Pregnancy Calculator
Choose the calculation method
Pick LMP (Naegele’s Rule) or Conception Date.
Enter your date
Select the first day of your last menstrual period, or the conception date, using the day, month and year menus.
Select the baby gender (optional)
This is optional and only changes the message shown in your results.
Click "Calculate Timeline"
See your estimated due date, pregnancy week, time left, trimester, days pregnant, a milestone for this week and weekly advice.