Percentage Increase Calculator
Choose whether to add a percentage to a number or to measure how much one value grew into another, enter the figures and press Calculate. The guide below explains the formulas and walks through examples.
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Created by the Reeliy Editorial Team. Last updated: Oct 19, 2026
How to calculate percentage increase
A percentage increase tells you how much bigger a quantity has become compared with where it began. The starting value is the reference point, so it is the number you divide by.
percentage increase = (new − original) ÷ original × 100
- Subtract the original value from the new value.
- Divide the difference by the original value.
- Multiply by 100 to turn the ratio into a percentage.
When the new value is smaller than the original, the answer comes out negative: the quantity shrank. The percentage decrease calculator presents the same comparison from the other side.
Increasing a number by a given percentage
If you know the percentage and want the larger value, use a multiplier.
new value = original × (1 + percentage ÷ 100)
amount added = original × percentage ÷ 100
Raising 1,450 by 4.2% adds 1,450 × 0.042 = 60.90, so the new total is 1,450 × 1.042 = 1,510.90.
Using the calculator
- Increase by %: enter the original value and the percentage. The result shows the increased value and the absolute difference, which is the amount added.
- Percentage increase (x to y): enter the original and the new value. The result shows the percentage increase and the absolute difference between the two numbers.
Answers are rounded to two decimals. Whole numbers appear without decimals, everything else shows exactly two decimals (12.50%), and thousands are separated by commas. Negative inputs are not accepted, and the percentage mode needs an original value other than zero, since dividing by zero has no meaning.
Worked examples
Each of these can be checked by entering the numbers into the calculator.
A pay rise
A monthly salary moves from 3,200 to 3,392. The difference is 192, and 192 ÷ 3,200 = 0.06, so the raise is 6%. An hourly rate of 18.50 with an 8% raise becomes 18.50 × 1.08 = 19.98, which is 1.48 more per hour.
Business growth
A service had 12,500 monthly active users and now has 15,125. That is 2,625 more users, and 2,625 ÷ 12,500 = 0.21, a growth of 21%.
A price rise
An item costing 49.99 goes up by 6.5%. The increase is 49.99 × 0.065 = 3.24935 and the new price is 49.99 × 1.065 = 53.23935. Rounded to two decimals the calculator shows 53.24, with an absolute difference of 3.25.
Property value
A flat bought for 285,000 is now valued at 327,750. The gain is 42,750 and 42,750 ÷ 285,000 = 0.15, so the value has risen by 15%. This is the total change; to express it per year, use the CAGR calculator.
Successive increases compound
Two increases in a row do not add up, because the second percentage is applied to an already larger base. Rising 10% twice multiplies by 1.10 × 1.10 = 1.21, a total of 21%, not 20%. The same logic drives compound interest, where each period's growth is added to the base for the next period.
total growth = (1 + p₁ ÷ 100) × (1 + p₂ ÷ 100) × … − 1Multiply the result by 100 to read it as a percentage.
Percentage results shown here are arithmetic, not forecasts or financial advice. Read the disclaimer for how to use calculator results.
Common mistakes
- Dividing by the new value rather than the original value, which understates the growth.
- Confusing percent with percentage points: a rate going from 3% to 5% rose by 2 points but by 66.67% in relative terms.
- Adding percentages from different bases instead of multiplying the growth factors.
- Expecting a 50% increase to be undone by a 50% decrease. It is not: 100 becomes 150, and 50% off 150 is 75.
For questions such as "what is 15% of 200?" or "what percent is 30 of 120?", use the full percentage calculator.
Frequently asked questions
What is the formula for percentage increase?
Subtract the original value from the new value, divide by the original value and multiply by 100. Going from 80 to 100 gives (100 − 80) ÷ 80 × 100 = 25%.
How do I increase a number by a percentage?
Multiply it by 1 plus the percentage as a decimal. To add 15% to 200, calculate 200 × 1.15 = 230.
Why is my percentage increase negative?
A negative result means the new value is lower than the original, so the quantity decreased. From 3 to 2, the calculator shows -33.33%.
Why can't I calculate a percentage increase from zero?
The original value is the denominator, and dividing by zero is undefined. Growth from nothing can only be described as an absolute amount.
Is a 50% increase followed by a 50% decrease back to the start?
No. Starting at 100, a 50% increase gives 150 and a 50% decrease from there gives 75. To return to 100 you need a decrease of one third.
Cite this calculator and page
If you use this page in your work, you can cite it as:
Reeliy Editorial Team. (2026). Percentage Increase Calculator. Reeliy. https://reeliy.com/calculators/percent-increase-calculator“Percentage Increase Calculator.” Reeliy, 2026, https://reeliy.com/calculators/percent-increase-calculator.