Guide · Increase
Percentage Increase Calculator
Updated: June 2026
A percentage increase tells you how much bigger a number has become, measured against where it started. It is the figure behind a pay rise, a rent hike, a price bump or a year of revenue growth. The arithmetic is short, but the order of the steps matters, and the starting value — not the ending value — is always the reference point.
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The percentage increase formula
To measure the increase between an original value and a new, larger one:
You find the raw difference first, then express it as a fraction of the original, then scale to a percentage. The division by the old value is the part people most often get wrong — dividing by the new value gives a different, smaller answer that quietly understates the rise.
A worked example
Suppose a salary goes from £40,000 to £44,000. The difference is 44,000 − 40,000 = 4,000. Divide by the original: 4,000 ÷ 40,000 = 0.1. Multiply by 100 and you have a 10% increase. To go the other way and apply a known percentage, multiply by one plus the rate: a 10% rise on 40,000 is 40,000 × 1.10 = 44,000.
Applying an increase quickly
The fastest way to add a percentage is the multiplier method. Adding 15% means multiplying by 1.15; adding 7.5% means multiplying by 1.075. This beats finding the percentage and adding it separately, especially when you chain several rises together — two consecutive 10% increases multiply to 1.10 × 1.10 = 1.21, a 21% total rise, not 20%.
| Increase | Multiplier | Applied to 200 |
|---|---|---|
| 5% | 1.05 | 210 |
| 10% | 1.10 | 220 |
| 25% | 1.25 | 250 |
| 50% | 1.50 | 300 |
| 100% | 2.00 | 400 |
Why increase and decrease aren't symmetric
A common trap: if a price rises 20% and then falls 20%, you do not end up where you started. Starting at 100, a 20% rise gives 120, and a 20% fall from 120 gives 96. The reason is that each percentage is taken from a different base. The increase calculator and its companion decrease page both make the reference value explicit so the asymmetry never surprises you.
Where you'll use it
- Comparing this year's revenue, traffic or headcount to last year's.
- Working out a pay rise or a rent increase before signing anything.
- Tracking a price change and checking it against an advertised percentage.
- Measuring growth between any two readings — weight, followers, test scores.
Frequently asked questions
What is the percentage increase formula?
Subtract the original value from the new value, divide by the original value, then multiply by 100: (new − old) ÷ old × 100.
How do I calculate a 25% increase on a number?
Multiply by 1.25, or find 25% and add it on. A 25% increase on 80 is 80 × 1.25 = 100.
Can a percentage increase be over 100%?
Yes. If a value more than doubles, the increase exceeds 100%. From 50 to 150 is a 200% increase.
Do two 10% increases add up to 20%?
No — they compound. 1.10 × 1.10 = 1.21, so the total is a 21% increase.