Date Adjustment Calculator
Free, locally-processed date adjustment calculator for fast and secure results.
Runs locally in your browser
Your inputs are processed locally in your browser and are not uploaded or stored by us.
Add or subtract years, months, and days from any calendar date to find a future or past date.
How to use the Add / Subtract Date Calculator
- Enter your starting date.
- Choose whether to Add or Subtract.
- Enter the number of years, months, and days you want to adjust by.
- Select Calculate to see the resulting date.
Calculation methodology
Result Date = Starting Date ± (Years + Months + Days)
The calculator applies adjustments in order of magnitude: years and months are applied first. If the resulting month is shorter than the starting day (e.g., February 31), the date is clamped to the last valid day of that month. Finally, any day adjustments are added.
Worked example
Starting dateJanuary 31, 2026
OperationAdd
Months1
January 31 + 1 month = February 31
Since February only has 28 days in 2026, the result is clamped to the last valid day of the month.
Result: February 28, 2026
Notes
- How do leap years affect addition? If you add exactly 1 year to February 29, the result clamps to February 28 of the following (non-leap) year.
- Can I combine years, months, and days? Yes. For example, adding 1 year, 2 months, and 15 days is fully supported and evaluates sequentially.