Date arithmetic and calendar calculations

Expert

Use FileMaker's date functions to calculate durations, find weekday boundaries, handle fiscal periods, and format dates for display.

What you'll learn

  • How date subtraction and addition work in FileMaker
  • How to find the first and last day of a month or week
  • How to calculate working days between two dates

FileMaker stores dates as integers — the number of days since January 1, year 1. This means ordinary arithmetic works on dates: subtracting two dates gives days between them, and adding an integer to a date advances it by that many days. The built-in Date, Day, Month, Year, and DayOfWeek functions complete the toolkit.

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Date arithmetic basics

Subtracting two Date fields returns the number of days between them as an integer. Adding an integer to a Date field advances the date.

FileMaker Script
// Days between two dates
DueDate - InvoiceDate

// 30 days from today
Get ( CurrentDate ) + 30

// First day of next month
Date ( Month ( Get ( CurrentDate ) ) + 1 ; 1 ; Year ( Get ( CurrentDate ) ) )
JSON functions in calculationsAggregate functions in related and portal contexts

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