Enter Last menstrual period (LMP), Cycle length (days) and Method to review due date with this tool. The due date is a calendar estimate tied to an assumed gestational interval.
The date estimate is calculated from the entered cycle, last menstrual period, conception date or gestational reference using standard calendar intervals.The calculation links Last menstrual period (LMP), Cycle length (days) and Method to due date. The due date is a calendar estimate tied to an assumed gestational interval. It is not a prediction of the exact delivery day.
Enter Last menstrual period (LMP), Cycle length (days) and Method to review due date with this tool. The due date is a calendar estimate tied to an assumed gestational interval.
Estimate a pregnancy due date from the reference date and method selected in the form. Understand why changing the date basis can change the estimate.
The due date is a calendar estimate tied to an assumed gestational interval. It is not a prediction of the exact delivery day.
Prepare Last menstrual period (LMP), Cycle length (days) and Method. Choose the dating method first and enter the matching date rather than treating a conception date as a last-period date.
The due date is a calendar estimate tied to an assumed gestational interval. It is not a prediction of the exact delivery day. Cycle irregularity, uncertain dates and clinical dating can change the estimate. A clinician may revise it using pregnancy-specific information.
Use the full settings in the worked-example table. They produce Due Date: October 8, 2026. Compare the method and units as well as the displayed number.
The displayed relationship is The date estimate is calculated from the entered cycle, last menstrual period, conception date or gestational reference using standard calendar intervals. Choose the dating method first and enter the matching date rather than treating a conception date as a last-period date.
Cycle irregularity, uncertain dates and clinical dating can change the estimate. A clinician may revise it using pregnancy-specific information. For personal care, discuss the measurements and method with a qualified clinician.
Worked due date calculator example. Set Last menstrual period (LMP) = 2026-01-01; Cycle length (days) = 28; Method = Naegele's Rule (LMP). The corresponding output is Due Date: October 8, 2026. The due date is a calendar estimate tied to an assumed gestational interval.
Estimate a pregnancy due date from the reference date and method selected in the form. Understand why changing the date basis can change the estimate.
Choose the dating method first and enter the matching date rather than treating a conception date as a last-period date.
| Field | Example value | Entry check |
|---|---|---|
| Last menstrual period (LMP) | 2026-01-01 | Use the calendar date for this scenario; keep the comparison date explicit. |
| Cycle length (days) | 28 | Use the stated unit and the measurement required by this model. |
| Method | Naegele's Rule (LMP) | Select the method before interpreting the result; different modes answer different questions. |
Relationship used for this example: The date estimate is calculated from the entered cycle, last menstrual period, conception date or gestational reference using standard calendar intervals.
The due date is a calendar estimate tied to an assumed gestational interval. It is not a prediction of the exact delivery day.
| Output | Displayed result |
|---|---|
| Due Date | October 8, 2026 |
With these settings, due date is October 8, 2026. Use the same units and calculation mode when reproducing this example.
The due date is a calendar estimate tied to an assumed gestational interval. It is not a prediction of the exact delivery day. Cycle irregularity, uncertain dates and clinical dating can change the estimate. A clinician may revise it using pregnancy-specific information.
Replace the illustrative last menstrual period (lmp) value (2026-01-01) with your own value, then complete the other inputs for the same scenario. Choose the dating method first and enter the matching date rather than treating a conception date as a last-period date.