How to use this calculator
Enter a start date and whole years, months, weeks or days. Each unit has its own increment: years and months offer 1, 3, 5 and 10; weeks offer 1, 5, 10 and 20; days offer 1, 10, 30 and 90. On mobile, plus is above the number and minus below it. Swipe the one-number wheel to choose an increment, or focus it and use Up/Down, Home or End. Reset restores increment 1 for every unit.
Years and months are combined before clamping to the destination month. Weeks are seven calendar days. Weekends and public holidays are included.
Worked example
January 31, 2026 + 1 month = February 28, 2026. Adding 30 days instead gives March 2, 2026.
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