# Due Date Calculator

> Estimate a pregnancy due date from the last menstrual period, conception, ultrasound dating, or IVF embryo transfer.

Page: https://askcalculators.com/calculator/due-date-calculator/
Definition: https://askcalculators.com/calculator/due-date-calculator/definition.json
JSON Schema: https://askcalculators.com/calculator/due-date-calculator/schema.json
Version: 2.0.0
Maintained by: AskCalculators (software project; not a credentialed reviewer)
Qualified review: pending. Automated checks do not establish professional approval.
Page status: Live
Review status: Pending

## Use
Open the calculator page and enter values. Query-string parameters can restore and bookmark a calculation.
Example: https://askcalculators.com/calculator/due-date-calculator/?method=lmp&lmpDate=2026-06-01&cycleLength=28

## Inputs
- method: Dating method; type=select; required; default=lmp; values=lmp|conception|ultrasound|ivf
- lmpDate: First day of last menstrual period; type=date; required; default=2026-06-01; showWhen=method:lmp
- cycleLength: Average cycle length; type=number; required; default=28; min=20; max=45; showWhen=method:lmp
- conceptionDate: Known conception date; type=date; required; default=2026-06-15; showWhen=method:conception
- ultrasoundDate: Ultrasound date; type=date; required; default=2026-08-24; showWhen=method:ultrasound
- ultrasoundWeeks: Gestational age at ultrasound: weeks; type=number; required; default=12; min=0; max=42; showWhen=method:ultrasound
- ultrasoundDays: Additional days; type=number; required; default=0; min=0; max=6; showWhen=method:ultrasound
- transferDate: Embryo transfer date; type=date; required; default=2026-06-20; showWhen=method:ivf
- embryoAgeDays: Embryo age at transfer; type=select; required; default=5; values=3|5|6; showWhen=method:ivf

## Outputs
- dueDateResult: Estimated due date; format=date; primary
- conceptionDateResult: Estimated conception date; format=date
- lmpDateResult: Estimated LMP date; format=date
- earlyTerm: Early-term date (37 weeks); format=date
- lateTerm: Late-term date (41 weeks); format=date
- methodResult: Method used; format=text

## Formula
LMP: 280 days plus cycle adjustment; conception: 266 days; ultrasound: 280 days minus gestational age; IVF: 266 days minus embryo age.

## Rules
- Empty optional inputs are undefined, not zero.
- Hidden conditional inputs are ignored.
- Do not invent missing required inputs.

Notice: The due date is an estimate, not a guaranteed delivery date. Clinical dating may differ.