A percentage increase calculator adds a percent on top of an original value and returns the new value plus the size of the increase. Enter your starting number and the percentage to add, typical uses include raising prices, applying markups, projecting salary increases, or scaling any quantity up by a defined factor.
The formula is straightforward: new = original × (1 + percent ÷ 100). A 15% increase multiplies by 1.15; a 7.5% increase multiplies by 1.075. The "+ 1" inside the parentheses is what differentiates an increase from a plain percentage of the value.
Key takeaway
A percentage increase is a multiplier, not just an addition. Increasing by 20% means multiplying by 1.20. This framing matters because increases compound: two consecutive 10% increases give 21% total (1.10 × 1.10 = 1.21), not 20%. Whenever you see a series of percent increases, multiply the multipliers, don't add the percentages.
How it's calculated
The percentage-increase formula:
new value = original × (1 + percent ÷ 100)
Equivalently, you can compute the increase amount first and add it back:
increase amount = original × percent ÷ 100 new value = original + increase amount
Both routes give the same answer. The first is faster for mental math (one multiplication); the second makes the underlying logic clearer when teaching the concept.
For chained increases, multiply the factors: a 10% increase followed by another 10% increase gives 1.10 × 1.10 = 1.21, or 21% total, not 20%. This compounding effect is the heart of why interest, inflation, and population growth all curve upward over time.
Source: Elementary arithmetic, original × (1 + percent ÷ 100)
Examples
$200 increased by 15%
- Original value 200
- Increase 15%
$200 with a 15% markup becomes $230, a $30 increase. Mental shortcut: 10% of 200 is 20, half of that is 10, sum to 30 for 15%. Add to 200 to get 230. Common scenario for retail markups, where 15-20% is a typical wholesale-to-retail bump.
$50 increased by 8.5%
- Original value 50
- Increase 8.5%
$50 with an 8.5% increase becomes $54.25, a $4.25 increase. Roughly the size of a typical inflation-adjustment to a small fixed expense over a year or two of moderate inflation.
Frequently asked questions
How do I calculate a percentage increase?
Multiply the original value by (1 + percent ÷ 100). So a 25% increase on $80 is 80 × 1.25 = 100. Equivalently, calculate 25% of 80 (which is 20) and add it to 80. Both paths give the same answer; the multiplier form is faster for mental math.
What's the difference between a percent increase and percent change?
Percent increase assumes the value goes up and is expressed as a positive number. Percent change can be either positive (increase) or negative (decrease) and includes the sign. Mathematically they're the same formula, the difference is just framing. If you don't know in advance whether the new value is higher or lower, use percent change. If it's definitely going up, percent increase is the more natural label.
How do I reverse a percentage increase?
Divide by (1 + percent ÷ 100), not multiply by (1 − percent ÷ 100). A 20% increase from $100 takes you to $120; reversing requires 120 ÷ 1.20 = 100, which is correct. Multiplying $120 by 0.80 gives $96, which is wrong. This asymmetry is why a 20% drop doesn't undo a 20% rise, see the percentage change calculator for the full explanation.
Do percent increases stack additively?
No, they multiply. Two 10% increases give a 21% total (1.10 × 1.10 = 1.21), not 20%. Three 10% increases give 33.1%. The gap between additive and multiplicative widens as the percentages grow. This is the same compounding math that drives interest, growth rates, and inflation projections.