Math
Percentage Increase Calculator
Three ways to work with a percentage increase: apply a percent to a starting value, find the percent increase between an original and a final value, or reverse an increase to recover the original from the final value.
Each mode shows the multiplier, the amount added, and the formula with your numbers.
The starting amount.
For example 25 for a 25% increase.
Try an example
Result
Result
—
- Amount of increase
- —
- Multiplier
- —
- Original value
- —
- Final value
- —
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Study path
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Percentage increase formulas
A percent increase compares how much a value grew with where it started. The three formulas below are the same relationship rearranged for whichever quantity is missing.
| Question | Numbers | Answer |
|---|---|---|
| Increase 80 by 25% | 80 × 1.25 | 100 |
| Percent increase from 80 to 100 | (100 - 80) / 80 × 100 | 25% |
| Original before a 25% increase to 100 | 100 ÷ 1.25 | 80 |
| Increase 50 by 200% | 50 × 3 | 150 |
The multiplier shortcut
Adding p% is the same as multiplying by (1 + p/100). A 25% increase is × 1.25; a 200% increase is × 3. Reversing an increase divides by the same multiplier. Subtracting the percent from the final value is a common mistake: 100 minus 25% is 75, but the original was 80.
How to use it
- Pick the mode: apply an increase, find the percent between two values, or recover the original.
- Enter the two known numbers. Decimals are fine.
- Read the result plus the multiplier and the amount of increase.
- Open Show the work to see the formula with your values substituted.
How to read the answer
In forward mode the result is the new value after growth. In find-percent mode a positive percent is an increase and a negative one means the value actually fell. In reverse mode the result is the value before the increase, and the check line confirms multiplying it back gives the final value.
Common mistakes and edge cases
- Divide by the original value, not the final one, when finding a percent increase.
- To reverse an increase, divide by the multiplier; do not subtract the percent from the final value.
- A 100% increase doubles a value; a 200% increase triples it.
- Percent increase from 0 is undefined because there is no starting amount to compare with.
- Increases do not add: two 10% increases give 21%, not 20%.
Worked examples
Increase 80 by 25%
Forward
Result
100
Percent increase from 80 to 100
Find the percent
Result
25%
Original before 25% increase to 100
Reverse
Result
80
Large increase
Increase 50 by 200%
Result
150
Value fell instead
From 100 to 80 is negative
Result
-20%
Decimal values
Percent from 12.5 to 15.75
Result
26%
Zero increase
Increase 40 by 0%
Result
40
Undefined from zero
Original 0
Result
Error
Frequently asked questions
How do you calculate percent increase?+
Subtract the original from the final value, divide by the original, and multiply by 100. From 80 to 100: (100 - 80) / 80 × 100 = 25%.
How do I increase a number by a percentage?+
Multiply by (1 + percent/100). To increase 80 by 25%, multiply by 1.25 to get 100.
How do I find the original value before a percent increase?+
Divide the final value by (1 + percent/100). If 100 is the result of a 25% increase, the original was 100 ÷ 1.25 = 80.
Why is the reverse of a 25% increase not a 25% decrease?+
Because the base changes. 80 → 100 is +25% of 80, but 100 → 80 is -20% of 100. Percents always refer to the starting value.
What does a percent increase over 100% mean?+
The value more than doubled. A 200% increase means the final value is three times the original.
Can percent increase be negative?+
If the final value is smaller than the original, the formula gives a negative number, which is really a percent decrease.
About this calculator
- Written by
- mathcheck editorial team
- Last reviewed
- September 4, 2026
Method
- Uses the values entered by the user and stable formulas documented on the page.
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Last updated: September 4, 2026