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Arithmetic & Numbers

Percentage Change Calculator

Enter the old value and the new value. The calculator subtracts, divides the change by the old value and multiplies by 100, so you can see why a rise and an equal fall do not cancel.

Updated October 3, 2026Written and reviewed by Mateuss M.Method: how we calculate

Try an example:

Answer+25%

That is a percent increase.

Step-by-step working 3 steps

1
Find the change
```
100 − 80 = 20
```
2
Divide the change by the old value
```
20 ÷ 80 = 0.25
```
3
Multiply by 100
```
0.25 × 100 = 25%
```

How to use the percentage change calculator

Enter the starting (old) value.
Enter the finishing (new) value.
Read the percentage and whether it is an increase or decrease.
Open the steps to see the change divided by the old value.

Percent change

% change = (new − old) ÷ |old| × 100
New = old × (1 + % change ÷ 100)

A positive result is an increase, a negative one a decrease.

Worked examples

Each example below is generated by the same calculator you used above, so the working always matches the answer.

80 → 100

Answer+25%

That is a percent increase.

Step-by-step working 3 steps

1
Find the change
```
100 − 80 = 20
```
2
Divide the change by the old value
```
20 ÷ 80 = 0.25
```
3
Multiply by 100
```
0.25 × 100 = 25%
```

100 → 75

Answer−25%

That is a percent decrease.

Step-by-step working 3 steps

1
Find the change
```
75 − 100 = −25
```
2
Divide the change by the old value
```
−25 ÷ 100 = −0.25
```
3
Multiply by 100
```
−0.25 × 100 = −25%
```

250 → 262.5

Answer+5%

That is a percent increase.

Step-by-step working 3 steps

1
Find the change
```
262.5 − 250 = 12.5
```
2
Divide the change by the old value
```
12.5 ÷ 250 = 0.05
```
3
Multiply by 100
```
0.05 × 100 = 5%
```

Common mistakes to avoid

Dividing by the new value

The base is always the old value. Dividing by the new one gives a different number.

Assuming +X% then −X% returns to the start

The second percentage is taken from a different base, so you finish below where you began.

Mixing up percent and percentage points

A rate moving from 10% to 12% is +2 percentage points but +20% in relative terms.

Frequently asked questions

Can the result be more than 100%?

Yes. A value that more than doubles has increased by over 100%.

What if the old value is zero?

The percent change is undefined because it would divide by zero.