Due Date Calculator
Estimate an expected due date from the first day of the last menstrual period (LMP).
How to Use the Due Date Calculator
Enter the first day of the last menstrual period or another supported dating input to estimate a pregnancy due date.
Practical Example
Using a last menstrual period date, the calculator applies a standard pregnancy-length estimate to project an expected due date.
Factors That Affect the Result
Cycle length, ovulation timing and clinical dating can shift the estimated date. Ultrasound or medical assessment may provide a different due date.
Frequently Asked Questions
Is the due date exact?
No. It is an estimate.
Can cycle length affect the estimate?
Yes.
Should medical dating take priority?
Yes. Use professional guidance for pregnancy care.
Related Tools
- Pregnancy Calculator
- Conception Calculator
- Ovulation Calculator
- Pregnancy Weight Gain Calculator
- Date Calculator
Understanding Due Date Estimates
Pregnancy due dates are estimates rather than exact predictions. A common method counts about 40 weeks from the first day of the last menstrual period, while other estimates may use conception information or ultrasound measurements. Cycle length, ovulation timing and uncertainty about dates can shift the estimate. Only a small proportion of births occur on the calculated due date itself, so the result is better understood as a reference point within a broader expected window. Clinical care may adjust dating based on ultrasound findings and medical history. An online calculator cannot determine gestational age with the same context as a healthcare professional and should not be used to make medical decisions. For prenatal care, symptoms, medication questions or concerns about timing, rely on guidance from a qualified healthcare provider who can interpret the dates alongside clinical information.