Add or Subtract Days Calculator
Find the exact date instantly from any start date.
Quick answer
To find the date 30 days ago, start with today's date and subtract 30 days as calendar days. Because today changes every day, the exact answer changes every day too.
How the counting works
Date arithmetic usually uses calendar days. That means weekends are included unless you intentionally switch to a business-day calculator. When the count crosses month or year boundaries, the calculator continues through the calendar automatically.
Example
If today were March 31, subtracting 30 days would move backward into the prior month while still counting every calendar day.
Why month length matters
Some months have 28, 29, 30 or 31 days. That is why a fixed day count does not always land on the same day number of a later month. Leap years can also change answers around February.
Frequently asked questions
Does 30 days mean calendar days or business days?
Unless otherwise specified, it means calendar days. Use a business-days calculator if weekends should be excluded.
Why does the answer change tomorrow?
Because the starting point is today, and today changes every day.
What tool should I use for the exact answer?
Use the Add or Subtract Days Calculator for exact date arithmetic and the Business Days Calculator when weekends should be excluded.