Date, Time and Age Tools Client-Side & Private

Due Date Calculator

Calculate pregnancy estimated due date (EDD) based on last menstrual period (LMP) or conception date.

First Day of Last Menstrual Period (LMP)

Estimated Due Date (EDD):

Sunday, December 6, 2026

Calculated using 40-week clinical gestation standard.

How to Use the Due Date Calculator

Enter your parameters: Type, paste, or select your input values above.
View instant results: Calculations update in real time as you change values.
Copy or export: Click copy, download, or print to use your results immediately.

About this Tool

Calculate pregnancy due date and trimester timeline using standard Naegele rule medical calculation.

Gregorian Calendar & Business Day Calculation

Business Days = Total Calendar Days - Weekends (Sat/Sun) - US Federal Holidays

Calendar calculations compute exact day differentials while adjusting for leap years (divisible by 4, except century years unless divisible by 400) and standard US federal holiday shifts.

Worked Example: Project SLA Turnaround Example

Input:

Start Date: Monday, Oct 5 | End Date: Friday, Oct 30

Output:

20 Working Business Days (excluding 8 weekend days and Columbus Day)

Provides exact business turnaround dates for commercial contracts and legal SLAs.

Frequently Asked Questions

Which US federal holidays are excluded from business days?

Standard federal holidays include New Year Day, MLK Day, Washington Birthday, Memorial Day, Juneteenth, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving, and Christmas Day.

How do business days differ from calendar days in legal contracts?

Calendar days include every consecutive day from Sunday through Saturday. Business days exclude Saturdays, Sundays, and official statutory bank holidays.

How do leap years affect exact age calculations?

A solar year is approximately 365.2425 days. Leap years insert February 29 every 4 years, which our algorithm factors into exact year, month, and day age calculations.

Calculation Standards

Built in compliance with ISO 8601 international date representation and Title 5 US Code 6103 federal holiday schedules. For tax, legal, or medical advice, consult certified professionals.