Calculate from your last period
The classic method doctors use - calculate your due date from your last menstrual period date with personalized cycle length adjustment.
Calculate Due Date from Last Period
Enter your last menstrual period date and cycle length for personalized results
Average cycle length from first day of one period to first day of next period
How LMP Works
Standard Method
Used by doctors and medical professionals worldwide
Cycle Adjustment
Accounts for your unique cycle length
Easy to Remember
Most women track their period dates
Important Note
This calculation estimates ovulation based on your cycle length. For irregular cycles or more precise dating, consider tracking ovulation or using our conception date calculator.
Other Calculator Versions
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Frequently Asked Questions
Common questions about calculating due date from last menstrual period
How accurate is the last menstrual period method?
The LMP method is accurate for women with regular 28-day cycles. However, it assumes ovulation occurred on day 14, which varies between individuals and cycles.
What if my cycles are irregular?
If you have irregular cycles, this calculator may be less accurate. Consider tracking ovulation with basal body temperature or ovulation predictor kits for better accuracy.
Why do doctors use the LMP method?
Most women remember their last period date better than conception date. It's the standard method used in medical practice and provides a consistent reference point.
Should I adjust for my cycle length?
Yes! This calculator accounts for different cycle lengths. If your cycles are shorter or longer than 28 days, enter your average cycle length for a more accurate result.
What if I can't remember my exact last period date?
Try to estimate as closely as possible. Even a few days difference can affect your due date. You can also ask your healthcare provider about dating ultrasounds.