Math

Percentage Decrease Calculator

Calculate the percentage decrease between two numbers. See the formula, each step, and the final result.

Quick Answer

Percentage Decrease = ((Old Value − New Value) / Old Value) × 100. For example, going from 80 to 60 is a 25% decrease: ((80 − 60) / 80) × 100 = 25%.

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New Value

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Enter two values to calculate the percentage decrease.

About This Tool

The Percentage Decrease Calculator determines how much a value has dropped in percentage terms. It is the inverse of percentage increase and is essential for tracking price drops, budget cuts, weight loss, stock declines, and any other situation where a value has gone down.

The Percentage Decrease Formula

Percentage Decrease = ((Original Value − New Value) / Original Value) × 100. This gives you the drop as a percentage of the original amount. The result is positive when the new value is smaller than the original and negative when the new value is actually larger (meaning there was an increase, not a decrease).

Real-World Applications

Retailers use percentage decrease to advertise discounts. A shirt that was $80 now on sale for $60 has a 25% discount. Investors track portfolio drawdowns as percentage decreases from peak value. Dieters measure weight loss progress. Businesses monitor revenue declines quarter over quarter. The formula stays the same across all these contexts.

Percentage Decrease vs. Percentage Difference

Percentage decrease always uses the original (larger) value as the base. Percentage difference uses the average of both values as the base. These are different calculations that serve different purposes. Use decrease when you have a clear before-and-after relationship. Use difference when comparing two values without a time-based relationship.

Common Pitfalls

A 50% decrease followed by a 50% increase does not return you to the original value. If $100 drops 50% to $50, then increases 50%, you get $75 — not $100. This asymmetry catches many people off guard and is important to understand in financial contexts.

Frequently Asked Questions

How do I calculate percentage decrease?

Subtract the new value from the old value, divide by the old value, then multiply by 100. Example: from 200 to 150 is (200−150)/200 × 100 = 25% decrease.

What is the difference between percentage decrease and discount?

They are the same calculation. A discount is simply a percentage decrease applied to a price. A $100 item at 30% off costs $70, which is a 30% decrease.

Can a percentage decrease be more than 100%?

No. A value can only decrease by a maximum of 100%, which means it drops to zero. If a value goes negative, you are looking at more than 100% decrease only in mathematical terms.

Why does a 50% decrease then 50% increase not return to the original?

Because the increase is calculated on the reduced value. $100 drops 50% to $50. Then 50% of $50 is $25, giving you $75. The bases are different.

How do I reverse-calculate the original price from a discount?

Divide the sale price by (1 minus the decimal discount). If something costs $60 after a 25% discount: $60 / (1 − 0.25) = $60 / 0.75 = $80 original price.

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