Is this the right tool?
- Best for
- Estimating one due date from the most appropriate known basis, including LMP, conception, or IVF transfer timing.
- Choose another tool when
- Use Pregnancy Calculator to calculate gestational week as of today, or Pregnancy Conception Calculator to estimate a conception window.
Decision context
An expected date is not a delivery prediction
Due-date calculations translate a dating convention into a calendar date. Clinical assessment, not this page, determines how that estimate is used in care.
Use the date as an educational reference point and follow the timing and instructions provided by a prenatal-care professional.
Dating methods have uncertainty
No calendar method can perfectly establish timing for every pregnancy; clinical information can refine the expected date.
Expected is not exact
An estimated due date supports care planning but does not predict the exact day of delivery.
Illustrative scenario
A user enters the first day of an LMP and receives an expected date. They record it as a discussion point, then use their clinician's documented estimate for care decisions.
Method notes and further reading
Due Date Calculator links these resources for an expected date is not a delivery prediction. Use the original material when a decision depends on a current rule, a personal circumstance, or a professional standard.
- American College of Obstetricians and Gynecologists: Methods for Estimating the Due DateClinical dating guidance. This site does not provide prenatal care, ultrasound dating, or individualized medical assessment.Reviewed July 2026.
What this calculator does
The calculator applies a calendar rule to the supplied reference date and returns an estimated due date. It makes the chosen dating basis visible so the result is not mistaken for a confirmed delivery date.
When to use it
Use it to understand a standard timing estimate, to prepare questions for prenatal care, or to compare a date convention with an existing clinical record.
Inputs explained
- Method: the selected dating, conversion, or calculation approach.
- Date: the calendar date used as the starting point or known reference.
Formula or method
The model adds the conventional gestational interval to the selected reference date. It does not account for ultrasound measurements, irregular cycles, reproductive treatment, or clinician documentation.
Worked example
Changing the date basis changes the estimate. That is expected: a date based on LMP, a reported conception date, and a clinician's ultrasound may not have identical certainty.
How to interpret the result
An expected due date is an estimate, not a deadline or a prediction of delivery. Clinical teams may confirm or revise dates using information this page cannot evaluate.
Practical checks before using the result
- Use the first day of the last menstrual period when that is the method selected.
- Keep a clinician-provided estimated due date as the main reference and ask questions if it differs from this educational result.
Common mistakes
- Treating the estimated date as the date labor must start.
- Using the tool to decide whether symptoms need medical attention.
Limitations and disclaimers
These results are general estimates only and are not medical advice. Individual health, body composition, activity, menstrual history, pregnancy dating, medications, and clinical findings can change what is appropriate.
Related calculator context
Pregnancy Calculator provides estimated weeks and Pregnancy Conception Calculator explains a related backward date estimate.
Related glossary terms
These plain-English definitions can help you check the terms used in this calculator before relying on the result.
Frequently Asked Questions
Why is an expected due date not a delivery prediction?
No calendar method can perfectly establish timing for every pregnancy; clinical information can refine the expected date. An expected due date is an estimate, not a deadline or a prediction of delivery. Clinical teams may confirm or revise dates using information this page cannot evaluate.
Which selected date basis should be checked before reading the result?
Use the first day of the last menstrual period when that is the method selected. Keep a clinician-provided estimated due date as the main reference and ask questions if it differs from this educational result.
When should a due-date estimate be replaced by clinical records?
These results are general estimates only and are not medical advice. Individual health, body composition, activity, menstrual history, pregnancy dating, medications, and clinical findings can change what is appropriate.