Percentage Decrease Calculator

Use this for reductions, write-downs, or any total that shrinks by a known percent.

Decrease an amount

Starting amount and the percent change.

Decrease

Original amount

Amount remaining—

Decrease—

Worked example

An $80 bill decreases by 15%. The drop is $12, so $68 remains. The same method works for a 30% fall in website traffic: 10,000 visits becomes 7,000.

How is a decrease different from a discount?: The maths is the same. This page is framed around any shrinking number — usage, headcount, inventory — not a shop price tag.
Can the result go below zero?: A 100% decrease reaches zero. More than 100% goes negative, which is valid for some ledgers and not for quantities. Check the context before you use it.
How do I reverse a decrease?: You cannot just add the same percent back. After a 20% drop, you need a 25% increase to return to the original, because you are growing from a smaller base.