Pregnancy Calculator
Use our Pregnancy Calculator to find your due date, current week, and conception day. Track your pregnancy progress easily from the first day of your last period.
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A Pregnancy Calculator will give you an estimate of your due date and your current gestational age, depending on the first day of your last period. It uses the Naegele Rule and adds 280 days (40 weeks) to such date. The calculator also provides an estimated date of conception and a way of monitoring the progress of the pregnancy week by week, and as such is a valuable tool for a pregnant couple.
Work & Installation — Input to Output Summary:
A Pregnancy Calculator can be used to determine how many weeks you are into pregnancy and show when you are expected to give birth (EDD). The calculator approximates your due date by entering the first day of your last menstrual period (LMP), and then using an estimated gestation period of 280 days (or 40 weeks). It also detects your date of conception and your trimester. It is a tool founded on the Rule by Naegele, and it is effective among women whose monthly cycles are consistently 28 days. It can be used as a convenient guide on monitoring pregnancy progress, prenatal appointments, and developmental milestones. You should always remember that this is only an approximation - you should always verify due dates with your healthcare giver via ultrasound or medical examination.
Naegele’s Rule
\textrm{Due Day}=\textrm{LMP + 280 days}
Testing and Final Adjustments
To make the Pregnancy Calculator more accurate, test various LMP dates of varying cycle lengths (2435 days). Ensure that calculating leap years, date limits, timestamps, and time zones are correct. The date-picker inputs are easy to select. Confirm that the displayed due date, conception date, and week of pregnancy are displayed. Add easy-to-understand labels and automatic trimester changes (1st, 2 nd, 3rd). To help enhance UI, include a clear summary card with gestational weeks of the baby, the number of days to get to the due date, and the estimated conception period. Medical validation -280-day (40 weeks) - and localization (MM/DD/YYYY or DD/MM/YYYY). Checks that should be made during accessibility include compatibility with screen-readers, navigation with a keyboard, and a responsive mobile layout.
📊 Data Table Converter (Input → Output)
| Input Field | Description | Output |
|---|---|---|
| LMP (Last Menstrual Period) | First day of your last period | Estimated Due Date |
| Cycle Length | Average menstrual cycle (default 28 days) | Adjusted Due Date |
| Current Date | Today’s date | Current Week of Pregnancy |
| Output | Calculated EDD, Gestational Age, Conception Date | Pregnancy Summary |
🩺 Example Output Table:
| LMP Date | Cycle Length | Due Date | Conception Date | Current Week |
|---|---|---|---|---|
| Jan 1, 2025 | 28 days | Oct 8, 2025 | Jan 15, 2025 | 10 weeks |
Frequently Asked Questions - Pregnancy Calculator:
What is a pregnancy calculator?
It estimates your due date, conception date, and pregnancy week using your last menstrual period (LMP).
How does the pregnancy calculator work?
It adds 280 days (40 weeks) to the first day of your last menstrual period to estimate your due date.
What is Naegele’s Rule?
A formula used to estimate a baby’s due date by adding 7 days to LMP and 9 months ahead.
How accurate is this calculator?
It provides an estimate; actual due date may vary depending on ovulation and medical assessment.
Can irregular cycles affect accuracy?
Yes, irregular cycles may shift ovulation timing, altering the predicted due date.
Can I use it if I don’t know my LMP?
It’s less accurate; consult your doctor for an ultrasound-based due date.
What is the gestational age?
The number of weeks since the first day of your last menstrual period.
Can this help plan prenatal visits?
Yes, it helps schedule checkups according to pregnancy milestones.
Does every pregnancy last 40 weeks?
Most last about 38–42 weeks; 40 weeks is the standard average.
Can I track trimesters with this tool?
Yes, it divides your pregnancy into three trimesters for better monitoring.
