Percentage Change Calculator

How to use this calculator

1. Enter the original value — where the figure started, such as 120.
2. Enter the new value — where it ended up, such as 150.
3. Read the result above. The hero figure gives the percentage and says whether it is an increase or a decrease; the four figures beside it show the change in value, both inputs and the direction in words.

Both values must be in the same unit — compare two prices, two weights, two quantities or two scores, not one of each. Decimals and negative numbers are accepted. The calculation runs in the page as you type, and your figures are carried in the address bar so a result can be shared or bookmarked.

Already know the direction of the change? The dedicated Percentage Increase Calculator and Percentage Decrease Calculator show the multiplier alongside the result.

What do I need to enter?

• Original value — the figure you are measuring from, any number from −1,000,000,000,000 to 1,000,000,000,000. It is the base the change is divided by.
• New value — the figure you are measuring to, within the same range and in the same unit as the original.

What do the results show?

• Percentage increase or Percentage decrease — the main figure, as a size without a sign, rounded to two decimal places. The label gives the direction.
• Change in value — the new value minus the original, with a + or − sign.
• Original value, New value and Direction — your inputs again, and the direction in words: Increase, Decrease, No change, or Undefined from zero.
• Calculation — the formula with your numbers substituted in. If the original value is zero, the percentage shows "Not defined".

How percentage change is worked out

Percentage change compares the difference between a new value and an original value against the original value. A positive result is an increase; a negative result is a decrease.

For ordinary positive values the bars make no difference, so the formula is usually written with the original value used directly: (New − Original) ÷ Original × 100. The absolute change is simply New value − Original value.

Worked example: a percentage increase

Worked example: a percentage decrease

A decrease is shown as 15% decrease rather than −15% decrease: the word already carries the direction, so the extra minus sign only reads as a double negative. The signed form −15% appears in the working line under the inputs.

Why the original value matters

A rise from 100 to 150 is a 50% increase:

(150 − 100) ÷ 100 × 100 = 50%

But a fall from 150 back to 100 is a 33.33% decrease:

(100 − 150) ÷ 150 × 100 = −33.33%

Percentage increases and decreases are measured from different starting values, so an increase and an equal numerical decrease do not usually cancel each other out.

Starting from zero

Percentage change cannot be calculated from a starting value of zero, because the formula divides by the original value. When the original value is zero, the calculator shows the absolute change instead — a move from 0 to 50 reports a change of +50 and reports the percentage as not defined. When both values are zero it reports no change, without presenting a percentage.

Working with negative values

When either value is negative, the calculator uses the magnitude of the original value as the baseline. The change itself keeps its sign, so it still tells you whether the move was up or down.

Interpret negative-value results in the context of what the values represent.

Quick examples

Frequently asked questions