Money · Quick Maths
Percentage Increase Calculator
Instantly calculate percentage increases, decreases, differences, and reverse percentages. Click an example to load a real-world scenario, or enter your own values.
- ✓% increase, decrease, difference & reverse modes
- ✓Instant animated results as you type
- ✓Click real-world scenarios to explore instantly
Calculation mode
Calculate the new value after adding a percentage
New value = 100 × (1 + 15 ÷ 100)
Quick examples
Choose a mode, enter your values and hit Calculate
Your full breakdown will appear here
A 5% salary increase on £40,000 adds £2,000 per year — but after tax, the real take-home gain is typically closer to £1,300–£1,500.
1.15×
is the multiplier for a 15% increase — multiply any value by 1.15 to find the result instantly
÷1.2
is how you reverse a 20% increase — divide the final value by 1.2 to get the original
Rule 72
divide 72 by an annual % growth rate to estimate how many years it takes a value to double
How each mode works
The calculator has four modes — each solves a different type of percentage problem.
Percentage increase
New value = A × (1 + B ÷ 100)e.g. 100 + 15% = 115
Use this to find a new price after a markup, calculate a salary after a raise, or see how a value grows by a fixed percentage.
Percentage decrease
New value = A × (1 − B ÷ 100)e.g. 200 − 20% = 160
Find the sale price after a discount, calculate a value after depreciation, or see the impact of a percentage reduction.
Percentage difference
% change = (B − A) ÷ A × 100e.g. 80 → 100 = +25%
Find how much one value has changed relative to another. Use for year-on-year comparisons, stock price changes, or revenue growth.
Reverse percentage
Original = Final ÷ (1 + B ÷ 100)e.g. 115 after +15% → 100 original
Work backwards from a final value to the original. Useful for finding the pre-tax price from a VAT-inclusive amount, or the original price before a discount.
Real-world use cases
Percentages appear constantly in everyday life — here are the most common situations where this calculator helps.
Salary negotiations
Use % increase to calculate exactly how much a 3%, 5%, or 10% pay rise adds to your salary in real pounds or dollars.
Shopping discounts
Use % decrease to find the final sale price after any discount — no mental arithmetic needed.
Investment returns
Use % difference to track how much your portfolio or individual stocks have grown from purchase price to today.
Property values
Compare house prices year on year — quickly find the % increase or decrease in any property value.
VAT & tax
Use reverse percentage to strip VAT from an inclusive price. Divide the final price by 1.2 to remove 20% VAT.
Business metrics
Track revenue growth, margin changes, conversion rate shifts, and cost increases month over month.
How to calculate a percentage increase
A percentage increase tells you how much a value has grown relative to its original amount. The formula is straightforward: multiply the original value by (1 + percentage ÷ 100).
For example, to find a 15% increase on 200: 200 × 1.15 = 230. The amount added is 30, and the new value is 230. This applies equally to salary increases, price markups, or any other value that grows by a percentage.
How to calculate a percentage decrease
A percentage decrease follows the same logic in reverse. Multiply the original by (1 − percentage ÷ 100). A 20% discount on a £250 item: 250 × 0.80 = 200.
This is one of the most misunderstood percentage calculations. A 20% increase followed by a 20% decrease does not return you to the original value — it leaves you slightly below, because the decrease is applied to the larger number. Use the % difference mode to check the net change.
How reverse percentage works
Reverse percentage is used when you know the final value after a percentage has already been applied, and you want to recover the original. The formula is: Original = Final ÷ (1 + percentage ÷ 100).
A common example is removing VAT from a price. If an item costs £120 including 20% VAT, the pre-VAT price is 120 ÷ 1.20 = 100. A common mistake is to simply subtract 20% from £120 — that gives £96, not the correct £100. Always divide, not subtract.
FAQ
What is the difference between percentage change and percentage difference?
Percentage change is directional — it measures change from a specific starting point (A to B). Percentage difference is often used symmetrically between two values with no defined starting point. In practice, the two are often used interchangeably to mean the same calculation.
Can I calculate a negative percentage increase?
Yes — entering a negative percentage in the increase mode is equivalent to a decrease. The calculator handles this correctly. Alternatively, switch to % decrease mode for clearer labelling.
How do I find what percentage one number is of another?
Use the % difference mode with the smaller number as A and the larger as B. The result tells you the percentage change from one to the other. To find X as a percentage of Y directly, divide X by Y and multiply by 100.
Why does a 50% increase followed by a 50% decrease not equal zero?
Because each percentage is applied to a different base. A 50% increase on 100 gives 150. A 50% decrease on 150 gives 75 — not 100. The net effect is a 25% loss. This is why compounding works the way it does.
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