Measure consistently
Choose the method that matches the documented event and enter the exact calendar date; use cycle length only with the LMP method.
Multi-method due-date calculator
Use the dating method you actually know.
Calculate an estimated due date from LMP, conception/ovulation, or a day-3 or day-5 embryo transfer, with method-specific offsets shown alongside the result.
The calculation runs locally in this browser. Educational outputs do not replace professional assessment, diagnosis, treatment or emergency care.
Method and interpretation guide
Use the due-date result as a transparent estimate
Choose the method that matches the documented event and enter the exact calendar date; use cycle length only with the LMP method. The worksheet exposes its assumptions so the result can be checked instead of accepted as a black box.
Read the assumptions
Different methods start from different biological or calendar events, which is why their offsets differ. Do not combine methods or repeatedly change the date without clinical criteria.
Escalate important decisions
A calculator cannot examine symptoms, medical history, medication effects or measurement quality. Use qualified professional guidance when the decision has health consequences.
Local calculation
Inputs are processed in this browser. No account or external calculator is required to produce the result.
False precision
Extra decimal places do not remove biological variation, input error or limits in the underlying population equation.
Scope
Different methods start from different biological or calendar events, which is why their offsets differ. Do not combine methods or repeatedly change the date without clinical criteria.
Simple by design
Three steps to a clearer number.
Enter your details
Use realistic values in each field. You can change them anytime.
Calculate instantly
The formula runs locally, so there is no account or waiting time.
Use the result
Treat the answer as a practical estimate for your next decision.