Percentage Increase Calculator
Increase any number by a percentage and see the new total, the amount added and the multiplier that produces it.
How it works
Increasing by a percentage means multiplying by one plus that percentage as a decimal. A 15% rise is a multiplication by 1.15 — not an addition of 15, which is the mistake that turns a percentage into a flat amount.
The multiplier form matters when increases stack. Two consecutive 10% rises are ×1.1 × ×1.1 = ×1.21, a 21% increase overall rather than 20%, because the second rise applies to the already-increased figure.
The formula
New value
new = original × (1 + percent ÷ 100)
Amount added
added = original × (percent ÷ 100)
Reversing it
original = new ÷ (1 + percent ÷ 100)
Worked examples
| Scenario | Working | Result |
|---|---|---|
| 250 increased by 15% | 250 × 1.15 | 287.5, up by 37.5 |
| A 40,000 salary with a 7% rise | 40000 × 1.07 | 42,800 |
| Two consecutive 10% rises | ×1.1 × ×1.1 | +21%, not +20% |
When you'd use it
- Applying a pay rise or a price increase
- Adding a markup to a cost price
- Projecting growth at a fixed rate
- Adding tax or a service charge
Common questions
Do two 10% increases make 20%?
No — they make 21%. The second increase applies to the already-increased figure, so the multipliers compound: 1.1 × 1.1 = 1.21. This gap widens quickly with larger percentages or more steps.
How do I reverse a percentage increase?
Divide rather than subtract. If 115 is the result of a 15% increase, the original is 115 ÷ 1.15 = 100. Subtracting 15% from 115 gives 97.75, which is wrong — a common and expensive error on invoices.
Is a 100% increase the same as doubling?
Yes. A 100% increase multiplies by 2. A 200% increase multiplies by 3, not 2 — the percentage describes what is added, not the final multiple.