Percentage Increase Calculator
How much did it change? Compare any two numbers, work backwards from a percentage, or find a share of the whole.
Find the difference
Percentage change = (new − original) ÷ |original| × 100. If the original is zero, the percentage is undefined.
From 100 to 125 is an increase of 25%.
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Calculation summary
Gross estimates only. Not payroll or tax advice.
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How to calculate percentage increase between two numbers
To calculate percentage increase, subtract the original number from the new number, divide by the original number, then multiply by 100. For example, an increase from 80 to 100 is (100 − 80) ÷ 80 × 100 = 25%. A move from 100 to 80 is a 20% decrease. The standard formula assumes a nonzero starting value:
For a negative original value, this calculator divides by the absolute magnitude of the original to show signed change. This is a chosen convention, not the same as the conventional formula that divides by the signed original. Starting from zero makes a relative percentage change undefined. Comparing a salary before and after a raise? Use the pay raise calculator to see the change across pay periods.
Percentage change between two numbers: examples
Use Percent change to compare old and new values, whether the result is an increase or a decrease. This is different from Part of whole, which asks what portion one number represents of another.
| Original | New | Result |
|---|---|---|
| 80 | 100 | 25% increase |
| 100 | 80 | 20% decrease |
| 150 | 165 | 10% increase |
How to add or subtract a percentage
Choose Add / subtract in the calculator to apply a rate to the number, rather than compare two different values. This works for percentages above 100% as well as ordinary positive and negative rates.
How to add a percentage to a number
To increase 240 by 15%, use 240 × (1 + 15 ÷ 100) = 276. The extra amount is 36. For a 10% increase on 100, the result is 110.
How to subtract a percentage from a number
To reduce 240 by 15%, use 240 × (1 − 15 ÷ 100) = 204. That is 36 less than the original, not 15 less. A 10% reduction from 100 gives 90. Subtracting 15 percentage points from an existing percentage is a different operation.
Reverse percentage calculator: find the original value
To find the original number before a percentage increase or decrease, divide the final number by (1 + rate ÷ 100). For example, a final value of 110 after a 10% increase started at 100. You cannot uniquely reverse a 100% reduction, because every original value becomes zero.
How to calculate the percentage of two numbers
First decide whether you need percentage change or part of a whole. To find what percent a part is of its total, divide the part by the whole and multiply by 100: 25 out of 200 is 12.5%. Enter 25 as Part and 200 as Whole in the calculator. Reversing them produces 800%, not 12.5%; the whole cannot be zero.
If you are instead asking how much a number increased from 25 to 200, choose Percent change. That change is (200 − 25) ÷ 25 × 100 = 700%, not 12.5%. The choice of starting value or whole matters more than the wording of the search query.
How to calculate percentage increase in Excel
Put the original number in A2 and the new number in B2. In C2, enter =(B2-A2)/A2, then format C2 as a percentage. To avoid a division-by-zero error, use =IF(A2=0,"Undefined",(B2-A2)/A2) instead. This standard spreadsheet method divides by the signed original; for negative starting numbers, its sign can differ from this calculator's absolute-denominator convention.
Percentage points vs. percentage change
Moving from 20% to 25% is an increase of 5 percentage points, but a 25% relative increase (5 divided by 20). They are not interchangeable.
Frequently asked questions
What is the percentage increase from 80 to 100?
(100 − 80) ÷ 80 × 100 = 25%.
How do you calculate percentage increase?
Subtract the starting value from the ending value, divide by the starting value and multiply by 100. For instance, moving from 40 to 50 is a change of 10, and 10 ÷ 40 × 100 = 25%. If the starting value is zero, no relative percentage increase can be defined.
Can a percentage increase be negative?
Yes. A negative result describes a decrease when the original value is positive.
What if the starting number is zero?
The change in amount can still be calculated, but the relative percentage change is undefined because division by zero is not possible, including a change from 0 to 0.
How to find percentage change from two values?
Choose the starting value as your denominator. Going from 150 to 120 changes by −30, and −30 ÷ 150 × 100 = −20%. To find the percentage between two numbers, decide which is the original value; swapping them gives a different answer.
How do you calculate the percentage of two numbers?
If one number is a part of the other, divide the part by the whole. For example, 30 is 15% of 200. If the numbers are a before-and-after pair, divide their difference by the original number instead; those are not interchangeable questions.
How is percentage change different from percentage of a whole?
A change from 80 to 100 is a 25% increase relative to 80. But 25 out of 200 is 12.5% of the whole. Use Percent change for before-and-after values, and Part of whole for ratios.
Related calculators
Calculating a raise at work? Use the pay raise calculator. To project your annual salary over several years, use the future salary calculator.
Methods and sources
See OpenStax: percent increase and decrease for the standard positive-baseline method. This tool's absolute-denominator treatment of negative starting numbers is a separate convention explained above.
Maintained by RaiseCalc. Calculation notes updated . See our precision and calculation limits, or report a calculation issue.