What this calculator does
A percentage decrease calculator answers one of two everyday questions: what a value becomes after it drops by a given percentage, or what percentage a value has dropped by, given the before and after figures. Discounts, pay cuts, weight loss targets and falling metrics all reduce to this same calculation.
The formula for percentage decrease is (old − new) ÷ old × 100. It is easy to mix up with the percentage-decrease formula for finding a new value, which instead multiplies the original by (1 − decrease% ÷ 100). This calculator handles both directions so you never have to rearrange the formula by hand.
The formula
To find a new value, the original is multiplied by one minus the decrease expressed as a fraction. To calculate percentage decrease from two known values, the amount removed (old minus new) is divided by the original value and expressed as a percentage. If the new value is larger than the original, that is technically a percentage increase, and the calculator flags it rather than showing a nonsensical negative decrease.
| Term | Meaning |
|---|---|
| Original value | The starting figure before the decrease is applied. |
| Decrease % | How much smaller, as a percentage of the original, the new value is. |
| New value | The figure after the decrease has been applied. |
| Amount removed | The plain difference between the original and new values. |
The inputs explained
| Field | What to enter |
|---|---|
| Original value | The starting value, before any decrease. |
| Calculate | Choose whether you know the percentage and want the new value, or know both values and want the percentage. |
| Percentage decrease (used when solving for new value) (%) | The percentage to subtract, only used when solving for the new value. |
| New value (used when solving for % decrease) | The value after the decrease, only used when solving for the percentage decrease. |
When to use it
Working out a sale price
A discount is a percentage decrease applied to the original price. Entering the price and the advertised discount gives the amount actually paid.
Checking how far a metric has fallen
Revenue, headcount, page views or any other tracked figure that drops between two periods can be expressed as a clean percentage rather than a raw difference, which makes it comparable across different starting sizes.
Reversing a markdown to see the original price
If a discounted price and the discount percentage are both known but the original price is not shown, solving for the percentage decrease direction with the two values confirms what the starting price must have been.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
What does a $1,000 value become after common percentage decreases?
The same starting value, reduced by a range of common percentages.
| Decrease | New value | Amount removed |
|---|---|---|
| 5% | 950.000 | 50.000 |
| 10% | 900.000 | 100.000 |
| 15% | 850.000 | 150.000 |
| 20% | 800.000 | 200.000 |
| 25% | 750.000 | 250.000 |
| 50% | 500.000 | 500.000 |
What percentage decrease took $500 down to a lower value?
The percentage decrease implied by a range of lower new values.
| New value | Percentage decrease | Amount removed |
|---|---|---|
| $450 | 10.0% | 50.000 |
| $400 | 20.0% | 100.000 |
| $350 | 30.0% | 150.000 |
| $300 | 40.0% | 200.000 |
| $250 | 50.0% | 250.000 |
| $200 | 60.0% | 300.000 |
Questions
How is percentage decrease different from percentage change?
Percentage decrease assumes the value went down and reports the drop as a positive figure. Percentage change can be positive or negative depending on direction. If you need a single figure that handles both directions automatically, see the percentage change calculator.
Why does reversing a percentage decrease not give back the original percentage?
A 20% decrease followed by a 20% increase does not return to the starting value, because each percentage is calculated on a different base. Decreasing $100 by 20% gives $80; increasing $80 by 20% gives only $96.
Can percentage decrease be more than 100%?
No, not for a positive value falling to zero or above. A decrease of 100% means the value has fallen to zero. Anything reported above 100% signals the new value has gone negative, which is unusual outside of things like account balances or temperature differences.
What if the new value is actually higher than the original?
That is a percentage increase, not a decrease, and the calculator will say so rather than show a negative decrease. Use the percentage increase calculator instead if that is the direction you are working in.
For the opposite direction, see the percentage increase calculator. For percentage-of-a-number and other everyday percentage questions in one tool, use the percentage calculator.