Date and Time Calculators
Pregnancy Due Date Calculator
Pregnancy Due Date Calculator estimate pregnancy due date from LMP, conception, IVF transfer, or ultrasound gestational age and show key milestones.
Date and Time Calculators
Pregnancy Due Date Calculator
Estimate pregnancy due date from LMP, conception, IVF transfer, or ultrasound gestational age and show key milestones.
Formula
ACOG convention uses 280 days from the first day of the LMP, adjusted by cycle length. Known conception uses 266 days. IVF uses transfer date + (266 - embryo age). Ultrasound uses scan date + (280 - gestational age in days).
About the Pregnancy Due Date Calculator
Estimate pregnancy due date from LMP, conception, IVF transfer, or ultrasound gestational age and show key milestones. Date and time calculators apply calendar-aware or duration-aware arithmetic to the dates, times, zones, and intervals requested by the form.
How the Pregnancy Due Date Calculator Works
ACOG convention uses 280 days from the first day of the LMP, adjusted by cycle length. Known conception uses 266 days. IVF uses transfer date + (266 - embryo age). Ultrasound uses scan date + (280 - gestational age in days).
The calculation runs in your browser. Submitted values are validated for the required numeric range, data shape, units, and method-specific restrictions before a result is shown.
Required Inputs
- Dating method (required) Options: First day of last menstrual period, Known conception date, IVF day-3 embryo transfer, IVF day-5 embryo transfer, Ultrasound date and gestational age
- Reference date (required)
- Usual menstrual cycle length (days) (optional)
- Gestational weeks on ultrasound date (optional)
- Additional gestational days on ultrasound date (optional)
Results Reported
The result panel shows the final answer together with the intermediate quantities needed to audit the calculation. Depending on this method, reported values include:
methodreference_dateestimated_due_dateestimated_conception_datetwelve_weekstwenty_weeksterm_begins_37_weeksforty_weeksgestation_length_daysclinical_note
Pregnancy Due Date Calculator Example
Use the example data button, calculate, then review the result table, formula, and worked solution before using the answer.
| Input | Example value |
|---|---|
| Dating method | lmp |
| Reference date | 2026-01-01 |
| Usual menstrual cycle length (days) | 28 |
| Gestational weeks on ultrasound date | 0 |
| Additional gestational days on ultrasound date | 0 |
How to Use the Calculator
- Confirm that the calculator title and method match the quantity, test, conversion, or planning question you need to solve.
- Enter values with compatible units and the requested sample, group, matrix, count, date, or option format.
- Select Example Data to inspect a valid input layout, or enter your own values and select Calculate.
- Review the result table, formula, worked substitutions, warnings, and interpretation rather than using only the headline number.
- Use Copy Result or Download CSV when you need a reusable record of the displayed calculation.
Understanding the Result
Calendar months, leap days, end-of-month rules, overnight intervals, and time zones are handled differently from fixed-length elapsed seconds.
Keep the entered values, units, selected options, and any warning shown beside the result. For a hypothesis test, report the statistic, degrees of freedom where applicable, p-value, alpha level, effect size, and decision. For an estimate or conversion, report the formula convention and final unit.
Accuracy and Limitations
The calculator keeps full browser precision during calculation and rounds only for display. Accuracy still depends on correct inputs and on whether the displayed model represents the real problem. Educational calculators cannot replace required professional review, current official rules, field measurements, laboratory methods, or specialist statistical software where those are necessary.
Frequently Asked Questions
What does the Pregnancy Due Date Calculator calculate?
Estimate pregnancy due date from LMP, conception, IVF transfer, or ultrasound gestational age and show key milestones.
Which formula does the Pregnancy Due Date Calculator use?
ACOG convention uses 280 days from the first day of the LMP, adjusted by cycle length. Known conception uses 266 days. IVF uses transfer date + (266 - embryo age). Ultrasound uses scan date + (280 - gestational age in days).
Is this a separate calculator?
Yes. This page has its own public URL, inputs, formula notes, browser function, fixture, and worked solution.
What should I verify before using the answer?
Check the entered values, units, selected options, formula convention, warnings, and result interpretation shown on this calculator page.