Due Date Calculator
Calculate the estimated due date for a pregnancy based on the first day of the last menstrual period (LMP) or the conception date. Also provides a timeline of key milestones.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the Due Date Calculator
- Select Calculation Method: Choose either Last Menstrual Period (LMP) or Conception Date from the dropdown.
- Enter the Date: Pick the corresponding date (LMP start or conception date) using the date input field.
- Adjust Cycle Length: Enter your average cycle length (default 28 days, range 20–45). This adjusts the due date if your cycle differs from 28 days.
- Set Luteal Phase: Enter your luteal phase length (default 14 days, range 10–16). This is typically 14 days.
- Calculate: Click the Calculate Due Date button. The estimated due date and key milestones (first trimester end, second trimester end, full term, late term) will appear below.
Note: All inputs are required and must be within the specified ranges. The calculator uses standard formulas (LMP + 280 days or conception + 266 days) with cycle length adjustments.
Previous Results
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Frequently Asked Questions
The due date is calculated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP), or 266 days (38 weeks) to the conception date. The calculation adjusts for cycle length differences from the standard 28-day cycle.
The calculator adjusts the due date by the difference between your average cycle length and 28 days. For example, if your cycle is 35 days, the due date is shifted 7 days later.
This calculator provides an estimate based on standard obstetric formulas. Actual due dates may vary. Always consult your healthcare provider for personalized medical advice.
