変化率計算機

What this tool does

Compare an original number with a new one and see the percent increase or decrease. Use it when a price, a score, or a measurement moved and you need the size of that move. Going from 80 to 100 is a 25% increase, while 100 back to 80 is a 20% decrease, because the starting numbers differ.

How to use

1. Enter the original value and the new value.
2. Press Calculate to see the percentage change.
3. A positive result is an increase. A negative result is a decrease.

Examples

• 80 to 100

  The value rose by 20, which is a 25% increase.

• 100 to 80

  The value fell by 20, which is a 20% decrease.

How it works

Percentage change is (new − original) ÷ original × 100. Going up 25% and then down 20% are not the same size of change, because the starting points are different.

Limitations

An original value of 0 is rejected, because the change is divided by that starting number. When both values are 0, the result is 0%. This page does not find a percent of a number or a discounted price.

See the disclaimer for what these tools do not cover.

FAQ

Is the Percentage Change Calculator free?

Yes. Comparing an original value with a new value to get the percent increase or decrease is free, and no account is required.

Why can’t I use 0 as the original value?

Dividing by zero is undefined. If both values are 0, the change is 0%. Any other new value from 0 cannot be expressed as a finite percentage.

Is my input sent to a server?

No. Both values are used only for the division on this page. Nothing is uploaded or stored.

What is the formula for percentage change?

Percentage change = (new value − original value) ÷ original value × 100. A positive result is an increase and a negative result is a decrease.

Why is a rise from 80 to 100 not the same as a drop from 100 to 80?

The change is divided by the starting number. 20 out of 80 is a 25% rise, while 20 out of 100 is a 20% drop.