Percentage Decrease Calculator

The decrease is 50. Dividing 50 by the original value of 200 and multiplying by 100 gives a percentage decrease of 25%. The original value is always the denominator in this calculation, never the new, smaller value.

Percentage decrease equals the original value minus the new value, divided by the original value, multiplied by 100. Written out: ((Original − New) ÷ Original) × 100. The key detail people get wrong is dividing by the new value instead of the original one, which produces the wrong percentage.

For normal positive values, a decrease all the way down to zero represents exactly a 100% decrease, which is the practical ceiling in most real situations. A final value that goes below zero can mathematically produce a percentage decrease above 100%, but that result rarely makes sense outside of specific technical or financial contexts.

Yes. A discount is simply a percentage decrease applied to a price. A 25% discount means the price drops by 25% of its original value, which is exactly the same math this calculator's discount mode uses to work out both the savings amount and the final sale price.

The original value is the fixed reference point the entire percentage is measured against. Percentage decrease describes how far a value fell relative to where it started, not relative to where it ended up, which is exactly why the same-sized numeric drop can represent very different percentages depending on how large the original value was.

Because each calculation uses a different starting point as its base. Dropping from 100 to 80 is a decrease of 20, measured against the original 100, giving 20%. Recovering from 80 back to 100 is an increase of 20, but now measured against a smaller starting point of 80, giving 25%. This asymmetry is one of the most common sources of confusion in percentage math, and it's exactly why a 50% pay cut needs a 100% raise, not a 50% raise, to fully recover.

Divide the final value by (1 minus the decrease percentage expressed as a decimal). For example, if a value of 320 represents the result of a 20% decrease, divide 320 by (1 − 0.20), which is 0.80, giving an original value of 400. This calculator's 'Find original value' mode performs that division automatically.

Percentage decrease specifically describes a drop, when the final value is lower than the original. Percentage change is the broader term that covers both directions, increases and decreases alike, usually expressed as a positive number for growth and a negative number for decline. If you need a single calculator that handles both directions automatically, a general percentage change tool is the better fit than one dedicated purely to decreases.