Pregnancy Results
This calculator gives an estimated pregnancy date. It is not a medical diagnosis.
Pregnancy Calculator – Calculate Pregnancy Weeks and Due Date
A Pregnancy Calculator helps estimate your pregnancy progress, expected delivery date, conception date, and remaining days until delivery. You can calculate pregnancy information using your last menstrual period (LMP), estimated due date, conception date, ultrasound results, or IVF transfer date. This makes it easier to understand your estimated pregnancy timeline in one place.
The calculator provides an estimate based on the dates and pregnancy details you enter. Actual pregnancy dates can vary, so use your healthcare professional’s advice for medical decisions.
What Is a Pregnancy Calculator
A Pregnancy Calculator is an online tool that estimates how far along a pregnancy may be and when the baby is expected to arrive. Pregnancy is commonly dated from the first day of the last menstrual period, rather than the actual conception date.
A typical pregnancy lasts around 40 weeks, or 280 days, from the first day of the last menstrual period. However, the estimated due date is not an exact prediction of the delivery day.
How to Use the Pregnancy Calculator
Follow these steps to calculate your estimated pregnancy dates.
Select the calculation method from the available options.
Enter the required date using the day, month, and year fields.
If you select Ultrasound, enter the pregnancy age in weeks and days shown by your ultrasound assessment.
If you select IVF Transfer, choose the embryo age, such as Day 3, Day 5, or Day 6.
Click the Calculate button to view your results.
Use the Reset button to clear the entries and start again.
Make sure the date you enter is correct. The calculator checks for invalid calendar dates and displays an error when the required information is missing or incorrect.
Available Pregnancy Calculation Methods
Last Period Date
This method uses the first day of your last menstrual period. The calculator estimates the due date by adding 280 days and estimates conception by adding 14 days to the period date.
This is a common method for estimating pregnancy dates, but it may be less accurate if your menstrual cycle is irregular or you do not remember the date correctly.
Estimated Due Date
If you already know your estimated due date, enter it directly. The calculator works backward to estimate the last menstrual period and conception dates.
The result depends on the due date you provide, so use the date recommended by your healthcare professional when available.
Conception Date
If you know your estimated conception date, enter it to calculate the expected due date. The calculator adds 266 days to estimate the delivery date and calculates the corresponding last menstrual period date.
Conception dates can be difficult to determine precisely, so this method may only provide an approximation.
Ultrasound
Choose the Ultrasound option if you have a scan date and a pregnancy age recorded in weeks and days. Enter both details to estimate the due date and pregnancy timeline.
Ultrasound measurements can help healthcare professionals assess pregnancy dating. The calculator uses the pregnancy age you enter and does not interpret ultrasound images or medical measurements.
IVF Transfer Date
This method is intended for pregnancies following an IVF embryo transfer. Enter the transfer date and select the embryo age: Day 3, Day 5, or Day 6.
The calculator uses the selected embryo age to estimate conception timing and the expected due date. Confirm your dates with your fertility clinic, as it can provide the most appropriate pregnancy dating for your treatment.
Pregnancy Calculator Results Explained
After you click Calculate, the tool displays the following information.
| Result | Meaning |
|---|---|
| Estimated Due Date | The estimated date of delivery |
| Conception Date | The estimated date of conception |
| Pregnancy Progress | The estimated number of completed weeks and additional days |
| Days Remaining | The number of days until the estimated due date, or the number of days past it |
| Trimester | An approximate pregnancy stage based on the calculated pregnancy age |
| Due Date | A second display of the same estimated delivery date |
The results are based on the method and information you provide. The tool does not confirm pregnancy, assess the baby’s health, or predict the exact date of delivery.
Understanding Pregnancy Weeks and Trimesters
Pregnancy progress is commonly measured in weeks and days. For example, 12 weeks and 3 days means 12 full weeks have passed, with three additional days.
The calculator uses these approximate stages:
First trimester: Before 14 weeks
Second trimester: From 14 weeks to before 28 weeks
Third trimester: From 28 weeks to before 40 weeks
Full term label in this calculator: 40 weeks or later
These are the calculator’s display categories, not a complete clinical classification. Medical definitions of term pregnancy include more specific stages, and the appropriate interpretation depends on your individual pregnancy.
If the calculated pregnancy start date is in the future, the tool displays pregnancy progress as not started.
How Is the Estimated Due Date Calculated
The calculator uses different date calculations depending on the selected method.
Based on the last menstrual period
Estimated due date = First day of the last menstrual period + 280 days
Based on conception
Estimated due date = Conception date + 266 days
Based on an existing due date
Estimated last menstrual period = Due date − 280 days
Estimated conception date = Due date − 266 days
Based on ultrasound
The calculator subtracts the entered pregnancy age in days from the ultrasound date to estimate the pregnancy start date. It then adds 280 days to estimate the due date.
Based on IVF transfer
The calculator subtracts the selected embryo age from the transfer date to estimate conception timing, then adds 266 days to estimate the due date.
These formulas are simplified estimates. A healthcare professional may adjust pregnancy dating based on menstrual history, ultrasound findings, or fertility treatment details.
Important Things to Know
A due date is an estimate, not a guarantee that delivery will happen on that day.
Irregular menstrual cycles and uncertainty about dates can affect the accuracy of a last-period calculation.
Ultrasound-based dating should be interpreted using the findings and advice of a qualified healthcare professional.
IVF pregnancy dating should be confirmed with your fertility clinic.
The calculator may show a negative number of days as days past due. This does not determine whether a pregnancy is overdue in a medical sense.
The results are for general information and should not replace professional prenatal care.
If you are pregnant or think you may be pregnant, consult a qualified healthcare professional for confirmation, prenatal care, and advice about your individual pregnancy timeline.
Pregnancy Calculator FAQs
A Pregnancy Calculator helps estimate your due date using the first day of your last menstrual period. It can also show your pregnancy week and estimated pregnancy timeline.
Enter the first day of your last period and click Calculate. The calculator typically adds 280 days to estimate your due date. The result is an estimate and may vary.
A Pregnancy Calculator provides an estimated due date, not an exact delivery date. Your menstrual cycle and ovulation timing can affect the estimate. Consult your healthcare provider for a more personalized assessment.
Yes. Depending on the calculator's features, it can estimate your pregnancy progress in weeks and days. This helps you understand your stage of pregnancy.
Yes. This online Pregnancy Calculator is free to use. Enter the required date to calculate your estimated pregnancy dates directly in your browser.