Add or Subtract Days Calculator

Calendar arithmetic that handles the edge cases

Manually adding days to a date gets tricky fast once month boundaries, varying month lengths, and leap years get involved - this calculator handles all of that automatically.

Worked example

For July 26, 2026, adding 100 days:

Result = 2026-11-03 (Tuesday)

Frequently asked questions

Can I subtract days instead of adding? Yes - enter a negative number of days to move backward to a past date instead of forward to a future one.

What is this commonly used for? Calculating contract deadlines, shipping arrival estimates, medical follow-up dates, legal notice periods, and any other scenario specifying "X days from" a known starting date.