Conception Date Calculator

Conception Date is evaluated from Calculate From, Date and Gestational Age. The calculation reports Estimated Conception Date, Conception Window - Earliest and Conception Window - Latest.

Results

Thanks — we’ve logged this for review.

About the Conception Date Calculator

Conception Date is treated here as a quantitative relation between Calculate From, Date, Gestational Age and Cycle Length - LMP method and Estimated Conception Date, Conception Window - Earliest and Conception Window - Latest.

The calculator uses a multi formula configuration. Each reported value is read as a direct evaluation of the stored rules with the declared field formats and units.

Formula basis:
From Due Date: Conception = EDD - 266 days
From LMP: Conception = LMP + 14 + (Cycle Length - 28) days

Interpret the outputs in the order shown by the result fields. Optional inputs affect only the outputs that depend on those variables.

Formula & How It Works

The calculation applies the following relations exactly as recorded in the metadata:

From Due Date: Conception = EDD - 266 days
From LMP: Conception = LMP + 14 + (Cycle Length - 28) days

Each output field is produced by substituting the supplied inputs into the relevant relation and then applying the declared rounding or text format.

Worked Examples

Example 1: From Known Due Date — Oct 15, 2024

Inputs

calc_method: due_date input_date: 2024-10-15
Estimated Conception Date: 2024-01-23. Conception Window - Earliest: 2024-01-20. Conception Window - Latest: 2024-01-26

With Calculate From = due_date and Date = 2024-10-15 as the stated inputs, the result is Estimated Conception Date = 2024-01-23, Conception Window - Earliest = 2024-01-20 and Conception Window - Latest = 2024-01-26. Each value corresponds to the declared output fields.

Example 2: From LMP — 28-Day Cycle

Inputs

calc_method: lmp input_date: 2024-02-05 cycle_length: 28
Estimated Conception Date: 2024-02-19. Conception Window - Earliest: 2024-02-16. Conception Window - Latest: 2024-02-22

With Calculate From = lmp, Date = 2024-02-05 and Cycle Length - LMP method = 28 as the stated inputs, the result is Estimated Conception Date = 2024-02-19, Conception Window - Earliest = 2024-02-16 and Conception Window - Latest = 2024-02-22. Each value corresponds to the declared output fields.

Example 3: From LMP — Long 35-Day Cycle

Inputs

calc_method: lmp input_date: 2024-01-10 cycle_length: 35
Estimated Conception Date: 2024-01-31. Conception Window - Earliest: 2024-01-28. Conception Window - Latest: 2024-02-03

With Calculate From = lmp, Date = 2024-01-10 and Cycle Length - LMP method = 35 as the stated inputs, the result is Estimated Conception Date = 2024-01-31, Conception Window - Earliest = 2024-01-28 and Conception Window - Latest = 2024-02-03. Each value corresponds to the declared output fields.

Example 4: From Current Gestational Age — 22 Weeks

Inputs

calc_method: gestational_age gestational_weeks: 22
Estimated Conception Date: 2025-12-18. Conception Window - Earliest: 2025-12-15. Conception Window - Latest: 2025-12-21

With Calculate From = gestational_age and Gestational Age = 22 as the stated inputs, the result is Estimated Conception Date = 2025-12-18, Conception Window - Earliest = 2025-12-15 and Conception Window - Latest = 2025-12-21. Each value corresponds to the declared output fields.

Common Use Cases

  • Find approximate conception date from known due date
  • Estimate conception from last menstrual period
  • Confirm conception date from current gestational age
  • Determine likely conception date for paternity planning