Due Date Naegele Calculator
Simplified Naegele280-day LMPconvention with explicitly caller-established cycle-length adjustment relative to28 days. Not a predicted birth date, calendar-month shortcut or clinically verified dating; irregular cycles/luteal duration may invalidate assumptions.
Description
A cycle-adjusted Naegele calculation shifts a recorded menstrual date by a conventional duration.
A cycle-adjusted Naegele calculation shifts a recorded menstrual date by a conventional duration.1
The cycle-length assumption does not establish ovulation or the best obstetric date.
When to use Due Date Naegele Calculator
Use this tool to calculate or review the supplied observations under the stated rules. Establish the observation date, units, measurement context and independently applicable clinical reference or calibrated model.
How to use Due Date Naegele Calculator and understand its results
- Establish the observation date, units, measurement context and independently applicable clinical reference or calibrated model.
- Enter independentlyRecordedLmpDate, callerVerifiedCycleLengthDays, using the field meanings and rules below, then run the tool.
- Read result.conditionalEstimatedDueDate. Use the units and sign conventions below.
- Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| independentlyRecordedLmpDate | Independently recorded lmp date | string | Required |
| callerVerifiedCycleLengthDays | Caller verified cycle length days | number | Required |
Parse a real Gregorian LMP date and require integer cycle length 15–60 days. Add 280+cycleLength−28 calendar days and reject a target outside years 0001–9999. This adopts a conventional cycle adjustment rather than independently establishing ovulation.
conditionalDueDate=LMPDate+(280+cycleLengthDays−28) calendar days Use the matching field units and the exact boundary, ordering and reference rules above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Structured result; its nested fields below contain the actual calculation or selected reference | object |
| result.conditionalEstimatedDueDate | Conditional Estimated Due Date | string |
{
"input": {
"independentlyRecordedLmpDate": "2026-01-01",
"callerVerifiedCycleLengthDays": 28
},
"output": {
"result": {
"conditionalEstimatedDueDate": "2026-10-08"
}
}
}Limitations and assumptions
Dating evidence, acquisition conditions and applicable clinical references remain independently established. The output describes supplied observations or a conditional model without diagnosing an outcome, choosing a dose or verifying clinical applicability.
Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Extremely large composite outputs are rejected.
Alternative or Complementary methods
For a related step, use Gestational Age From LMP Calculator: Gestational age from the last menstrual period counts elapsed calendar days from the recorded menstrual anchor. For a complementary comparison, use Gestational Age From Conception Calculator: Time since conception and obstetric gestational age use different date anchors.
References
-
Due Date Naegele Calculator — tool.io
Similar or alternative tools
- Gestational Age From LMP Calculator
Gestational age from the last menstrual period counts elapsed calendar days from the recorded menstrual anchor.
- Gestational Age From Conception Calculator
Time since conception and obstetric gestational age use different date anchors.