Pregnancy Due Date Calculator
When will you meet your baby? Enter the first day of your last period to calculate your Estimated Due Date, current trimester, and see how big your baby is today!
Your Details
Standard cycle is 28 days. Adjust if yours differs.
Estimated Due Date: Sunday, October 18, 2026
252 Days to go!
Estimated Due Date
Sunday, October 18, 2026
252 Days to go!
Your Baby is the size of a
Blueberry
About 1.3 cm
Likely Conception
Jan 25
Progress
10.0%
What is a Pregnancy Due Date Calculator?
A Pregnancy Due Date Calculator is a helpful prenatal planning tool that estimates your baby’s expected delivery date based on the first day of your last menstrual period (LMP) and your average menstrual cycle length. It gives you a clear timeline of your pregnancy journey from conception to delivery.
Along with the estimated due date, the calculator also shows important pregnancy milestones such as conception period, first trimester, second trimester, third trimester, and an approximate baby size based on the current week of pregnancy.
How Does the Pregnancy Due Date Calculator Work?
The calculator begins by using the first day of your last period as the starting point of pregnancy. Since ovulation usually occurs a few days after this date, the calculator adjusts the timeline based on your average menstrual cycle length.
Doctors typically calculate your due date from the first day of your last menstrual period (LMP). This is called Naegele's Rule. The standard pregnancy lasts about 280 days (or 40 weeks) from the LMP.
Using this information, it estimates your due date by adding the standard pregnancy duration and then breaks the timeline into trimesters. As pregnancy progresses, the calculator also provides an approximate comparison of your baby’s size to common fruits or everyday objects for easy understanding.
Is the Due Date exact?
Only about 4% of babies are born on their exact due date. Most are born within two weeks before or after. Consider this date an estimate to help you plan.
Pregnancy Due Date Formula (With Example)
The calculator is based on Naegele’s Rule, with adjustments for cycle length:
Estimated Due Date (EDD) = LMP + 280 days + (Cycle Length − 28 days)
Example:
First Day of Last Period (LMP): 1st January 2026
Average Cycle Length: 30 days
- Standard Pregnancy Duration = 280 days
- Cycle Adjustment = 30 − 28 = 2 days
- Estimated Due Date = 1st January 2026 + 282 days
- Estimated Due Date = 10th October 2026
Why use Cycle Length?
The standard calculation assumes a 28-day cycle with ovulation on day 14. If your cycle is longer (e.g., 32 days), you likely ovulated later, meaning your due date should be pushed later. Our calculator adjusts automatically for your unique cycle length.
Based on this timeline, the calculator also shows:
- Conception Window: Around mid-January 2026
- 1st Trimester: Weeks 1–12
- 2nd Trimester: Weeks 13–26
- 3rd Trimester: Weeks 27–40
- Baby Size: Displayed based on the current pregnancy week
Use Cases of a Pregnancy Due Date Calculator
- Estimating your baby’s expected delivery date
- Tracking pregnancy progress by trimester
- Planning prenatal appointments and check-ups
- Understanding key pregnancy milestones
- Monitoring baby growth stages week by week
- Preparing for maternity leave and delivery planning
Benefits of Using a Pregnancy Due Date Calculator
- Provides a quick and reliable due date estimate
- Helps visualize pregnancy stages and trimesters
- Adjusts calculations based on cycle length
- Makes pregnancy tracking simple and informative
- Useful for expecting parents and healthcare discussions
- Offers an easy-to-understand view of baby development
A Pregnancy Due Date Calculator helps expecting parents stay informed and organized throughout pregnancy by offering a clear timeline and meaningful insights into each stage of baby development.
Frequently Asked Questions
Find clear answers to common questions about this converter, accuracy, usage, and real-world applications.
What is a Pregnancy Due Date Calculator?
A Pregnancy Due Date Calculator estimates your expected delivery date based on the first day of your last menstrual period (LMP) and your average cycle length.
How accurate is the due date calculation?
The calculated due date is an estimate. Most pregnancies last around 40 weeks, but actual delivery can occur before or after the estimated date.
Why is the last menstrual period used instead of conception date?
The exact conception date is often unknown, while the first day of the last period is easier to track and provides a reliable reference for pregnancy dating.
Does cycle length affect the due date?
Yes, if your menstrual cycle is longer or shorter than 28 days, the calculator adjusts the estimated due date accordingly.
What do the trimester details mean?
The calculator divides pregnancy into three trimesters, helping you understand which stage of pregnancy you are in and what milestones to expect.
How is baby size shown in the results?
Baby size is displayed as an approximate comparison based on pregnancy week, making it easier to visualize growth and development.
Can this calculator track pregnancy progress week by week?
Yes, it shows ongoing pregnancy stages such as conception period, trimester progress, and expected due date as time advances.
Should this calculator replace medical advice?
No, this tool is for informational purposes only. Always consult a healthcare professional for medical guidance and prenatal care.
How accurate is this calculator?
This calculator uses the standard medical formula (Naegele's Rule) adjusted for cycle length. It is as accurate as a doctor's initial estimate, but an ultrasound scan is the most accurate way to date a pregnancy.
What if I don't know my cycle length?
If you are unsure, leave it at the default 28 days, which is the global average.
When does the first trimester end?
The first trimester technically ends at the completion of Week 13. The second trimester runs from Week 14 to Week 27.