Percent Increase Calculator

What this calculator does

Your rent went from 800 to 900. Your site went from 5,000 visitors to 8,000. The new number is bigger, and you want to put a figure on the jump. That is a percent increase: the rise between two values, measured as a percentage of where you started.

Type the starting value and the final value, and the tool works out the increase.

Using the calculator

1. Type the initial value, where you started.
2. Type the final value, where you ended up.
3. Press Calculate.

You will get the percentage along with the word "increase". The starting value cannot be zero, since there would be nothing to measure the change against. And if you happen to enter a final value that is actually smaller, the tool will simply tell you it is a decrease instead.

The formula | (rise ÷ original) × 100

The percent increase is:

((final value − initial value) ÷ initial value) × 100

Work out the rise, the final minus the initial, then ask what fraction that rise is of the original value, and turn it into a percentage. The key is that you divide by the starting value, not the final one. The increase is always measured against where you began.

A worked example | 70 to 120

Say something grew from 70 to 120.

1. The rise: 120 − 70 = 50.
2. As a fraction of the original: 50 ÷ 70 = 0.7143.
3. As a percentage: 0.7143 × 100 ≈ 71.43%.

So it is about a 71.43% increase. Notice the 50 is compared with the starting 70, not the ending 120, which is what makes it an increase rather than a smaller-looking figure.

Two increases do not add up

A trap worth knowing. If something rises 20% and then rises another 20%, the total is not 40%. Percentage increases multiply rather than add, because the second rise is measured against the already-larger amount. Starting at 100, a 20% rise gives 120, and a further 20% rise gives 144, which is a 44% increase overall, not 40%. The same reason explains why a 50% rise followed by a 50% fall does not bring you back to where you started: it leaves you at 75% of the original.

Increase, decrease, and change

Under the hood, an increase, a decrease and a general change are the same calculation: the difference between two values, measured against the starting one. This tool is framed for things going up. When a value falls, the percent decrease calculator is the natural fit, and when you just want the change in either direction, the percent change calculator handles both. For the wider set of percentage questions, see the percentage calculator.

Questions people ask

What is the percent increase from 70 to 120?

About 71.43%. The rise of 50, divided by the original 70, times 100.

What is the percent increase formula?

((final − initial) ÷ initial) × 100. The rise divided by the starting value, as a percentage.

Do I divide by the starting or the final value?

The starting value. A percent increase is always measured against where you began.

If something rises 20% twice, is that a 40% increase?

No, it is 44%. Percentage increases multiply, so 100 becomes 120 and then 144.

What if my final value is lower than my initial value?

Then it is a decrease, and the tool will say so. For that case the percent decrease calculator is the better fit.

References

A note on the idea behind it. A percent increase expresses the rise between two values as a fraction of the starting value, then as a percentage out of 100. Because each change is measured against its own base, successive increases combine by multiplying rather than adding. For further reading, see Relative change and difference.

1. Percent increase, the rise between two values divided by the starting value, expressed as a percentage.