Percentage Increase Calculator: Formula and Examples
Formula: (New Value minus Old Value) / Old Value x 100. Three numbers, one division, one multiplication. This article breaks the formula down, shows you five worked examples, and covers the reverse: finding the new value after a known increase.
The Percentage Increase Formula
To find how much something has grown in percentage terms, you compare the change to the original:
Percentage Increase = (New minus Old) / Old x 100
The numerator, New minus Old, is the raw amount of change. Dividing by the Old value puts that change in proportion to where you started. Multiplying by 100 converts the decimal to a percentage. All three steps matter.
Five Worked Examples
Example 1: Price rise at the grocery store
A box of cereal cost $3.50 last year. Now it costs $4.20.
Change: 4.20 minus 3.50 = 0.70.
Divide by old: 0.70 / 3.50 = 0.20.
Multiply by 100: 0.20 x 100 = 20%.
The price rose 20%.
Example 2: Salary raise
You earned $45,000 last year. This year your salary is $48,600.
Change: 48,600 minus 45,000 = 3,600.
3,600 / 45,000 = 0.08.
0.08 x 100 = 8% raise. Not bad.
Example 3: Website traffic
Last month you had 1,200 visitors. This month you have 1,500.
(1,500 minus 1,200) / 1,200 x 100 = 300 / 1,200 x 100 = 25% increase.
Example 4: Stock price
A share bought at $42 is now worth $63.
(63 minus 42) / 42 x 100 = 21 / 42 x 100 = 50% increase.
Example 5: Partial year comparison
Q1 revenue: $180,000. Q2 revenue: $216,000.
(216,000 minus 180,000) / 180,000 x 100 = 36,000 / 180,000 x 100 = 20% quarter-on-quarter growth.
Quick Reference Table
| Old Value | New Value | Change | Percentage Increase |
|---|---|---|---|
| 100 | 110 | +10 | 10% |
| 200 | 250 | +50 | 25% |
| 80 | 120 | +40 | 50% |
| 50 | 100 | +50 | 100% |
| 1,000 | 1,350 | +350 | 35% |
Finding the New Value After a Known Increase
Sometimes you know the percentage and want to find the resulting value, not the percentage itself. The reverse formula is:
New Value = Old Value x (1 + Percentage / 100)
A 15% increase on $320: 320 x (1 + 0.15) = 320 x 1.15 = $368.
A 40% increase on 75: 75 x 1.40 = 105.
This is covered in more depth in our article on how to add a percentage to a number.
What Does 100% Increase Actually Mean?
It means the value doubled. If sales rise by 100%, the new figure equals twice the original. A 200% increase means it tripled. People sometimes use "200% growth" when they mean it doubled, so watch for context. The formula makes it clear: 100% increase on 50 is (New minus 50) / 50 x 100 = 100, which gives New = 100.
Compounding: Why Multiple Increases Do Not Simply Add Up
If a price rises 10% one year and 10% the next, the total increase is not 20%. It is 21%. A $100 item becomes $110 after year one, then $121 after year two. The second 10% is applied to the larger base. For a deeper look at how percentage changes combine, see our guide on percentage change between two numbers.
Using the Free Calculator
The percentage calculator on the homepage computes percentage change instantly. Enter the old and new values in the "percent change" section and the result shows up immediately, with the direction (increase or decrease) labelled for you.
Frequently Asked Questions
What is the formula for percentage increase?
Percentage increase = (New Value minus Old Value) / Old Value x 100. A rise from 50 to 65 is (65 minus 50) / 50 x 100 = 30%.
How do I add a percentage increase to a number?
Multiply the original by (1 plus the decimal form of the percentage). A 20% increase on 150 is 150 x 1.20 = 180.
Is a 100% increase the same as doubling?
Yes. A 100% increase means the amount went up by the full original value, so the new total is twice the original.
How do I calculate a salary raise as a percentage?
Subtract the old salary from the new, divide by the old, multiply by 100. A raise from $45,000 to $48,600 is (48,600 minus 45,000) / 45,000 x 100 = 8%.