How do I calculate a negative change?

The formula is the same. A negative result indicates a decrease. Example: from 500 to 400 = −20%.

Calculate Percentage Change Between Two Values

Calculate percentage change

What is the change between two values?

Initial value

→

Final value

Result

The change measures how much it moved from the starting point. Formula: (new − old) ÷ old × 100. If positive it increases, negative it decreases. Tip: think of your old price as the reference, it's always the basis.

How to calculate a percentage difference

The percentage change (or rate of change) measures the magnitude of the shift between two values. It's the go-to tool for comparing prices, analysing revenue growth, measuring how an indicator has evolved, or comparing two performances. The formula is: Change = (Final value − Initial value) / |Initial value| × 100.

A positive result indicates an increase, a negative result a decrease. For example, a rent going from €800 to €850 has increased by (850 − 800) / 800 × 100 = +6.25%. Revenue going from €50,000 to €45,000 has decreased by (45,000 − 50,000) / 50,000 × 100 = −10%.

Important: the change is not symmetrical. A 50% increase followed by a 50% decrease does not return to the initial value. If 100 increases by 50%, you get 150. If 150 decreases by 50%, you get 75, not 100. This is why the initial value is always used as the reference in the calculation.

Frequently asked questions

Percentage change = (Final value − Initial value) / |Initial value| × 100. For example, from 80 to 100: (100 − 80) / 80 × 100 = +25%.

The formula is the same. If the final value is less than the initial value, the result is negative. For example, from 500 to 400: (400 − 500) / 500 × 100 = −20%. This means a 20% decrease.

Change (rate of change) is a percentage relative to the initial value. The gap is the absolute difference between two values (in units). For example, from 80 to 100: the gap is 20, the change is +25%.

Because the basis changes. 100 + 50% = 150. Then, 50% of 150 = 75, so 150 − 75 = 75, not 100. The decrease applies to the new value, not the old one.

Calculate Percentage Change