Percentage Increase Calculator

This calculator works out the percentage increase between any two numbers, whether that is a price rise, a pay increase, a rent review, or growth in sales, visitors or any other measure between two periods. You enter two figures: the original (old) value and the new value. The calculator instantly returns the percentage increase, shown as a large percentage figure, along with a plain-English summary of the actual amount the value has risen by and the two figures you compared. It updates live as you type, so you can test different scenarios without pressing a button. If you enter a new value that is lower than the original, the calculator switches automatically to show a percentage decrease instead, so the same tool works for falls as well as rises. Underneath the calculator you will find the formula it uses (new minus old, divided by old, multiplied by 100), a worked New Zealand example using a weekly rent rise, and a separate explanation of how to increase a number by a percentage if you already know the percentage and need to work forward to a new figure. Use this tool whenever you need to express a change as a clear percentage figure, for pay negotiations, comparing quotes, tracking business growth or checking how much a bill or rent has actually gone up.

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20% increase
An increase of 10 (from 50 to 60)

If the new value is lower than the original, the result is shown as a percentage decrease.

How to calculate a percentage increase

Subtract the original value from the new value to get the change, divide that change by the original value, then multiply by 100. In short, percentage increase equals (new minus old), divided by old, times 100.

Worked New Zealand example

A weekly rent rises from $500 to $540. The change is $40. Divide $40 by the original $500 to get 0.08, then multiply by 100. That is an 8% increase.

To go the other way and increase $500 by 8%, multiply $500 by 1.08, which gives $540.

Increase a number by a percentage

To increase a value by a percentage, multiply it by 1 plus the percentage as a decimal. For example, to add a 15% margin to a $200 cost, multiply $200 by 1.15 to get $230.

Frequently asked questions

Percentage increase or percentage change?

They use the same formula. Percentage change covers both rises and falls, so a negative result is a percentage decrease.

Why divide by the original value?

Because a percentage increase is always measured against the starting point. The same $10 rise is a bigger percentage when the starting value is small.

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