Date math
Date Calculator
Add or subtract days/weeks/months from a date, or compute the exact duration between two dates in years, months, and days.
How is this calculated?
Shift: result = base ± (years, months, weeks, days). Duration: end − start, displayed as Y/M/D plus total days/weeks/months.
Notes
- Source: Umm Al-Qura Calendar
- These calculators are for informational purposes only and are not financial, tax, legal, or professional advice. Verify the result with an official source or qualified advisor.
A simple but accurate date calculator. Add or subtract days, weeks, months, or years from a given date, or measure the exact duration between two dates — useful for project planning, contract terms, residency timelines, and visa calculations in Saudi Arabia.
How to use this calculator
- 1 Choose a mode: "Add or subtract from a date" or "Duration between two dates".
- 2 For shift mode, pick the base date, choose + or −, then set how many years, months, weeks, or days to move.
- 3 For duration mode, enter the start and end dates. The result shows years / months / days plus totals in days, weeks, and months.
Frequently asked questions
How do I add 30 days to a date?
Set mode to "Add or subtract from a date", pick your base date, choose Add, and enter 0 years / 0 months / 0 weeks / 30 days. The result date appears below. The result is bookmarkable and shareable.
How many days between two dates?
Set mode to "Duration between two dates", enter the start and end dates, and the calculator returns the total in days, weeks, months, and years — plus the breakdown as Y / M / D.
Does the calculator handle month length differences?
Yes. Adding "1 month" to 31 January correctly lands on 28 or 29 February, and adding "1 year" to 29 February 2024 lands on 1 March 2025 (since 2025 has no 29 Feb). The date math follows ISO calendar rules.