Percentage Increase Calculator

Percentage increase formula

To increase a number by a percentage, find that percentage of the number and add it on. Equivalently, multiply by a growth factor of one plus the percentage as a decimal:

amount of increase = original × (percentage ÷ 100)
new value = original × (1 + percentage ÷ 100)

The second form is handy because the factor can be reused: an 8% increase is always "× 1.08", a 25% increase is "× 1.25", and a 100% increase is "× 2".

Switch the mode to Find the % increase from old to new when you already know both values and want the rate instead: the tool divides the gain by the old value, (new − old) ÷ |old| × 100. Going from 250 to 270 is a 20-unit gain on a 250 base, an 8% rise. If the new value turns out lower, the result says so and points you to the decrease tool.

Worked examples

Example 1: an 8% raise on a $250 weekly wage

Amount of increase: 250 × 0.08 = 20. New value: 250 + 20 = 270. Using the factor: 250 × 1.08 = 270.

Example 2: adding 7.25% sales tax to $64.99

Tax: 64.99 × 0.0725 = 4.7118 (about $4.71). Total: 64.99 × 1.0725 = 69.7018, or $69.70 after rounding to the cent.

Example 3: a 40% markup on a cost of 18

Markup: 18 × 0.40 = 7.2. Selling price: 25.2. Note that a 40% markup on cost is not a 40% profit margin on price — the margin here is 7.2 ÷ 25.2 ≈ 28.6%.

How to read the result

The large figure is the new value after the increase, and the line beneath gives the amount added. The comparison bars show the original (blue) beside the new value (amber) so you can see the proportion visually; a 100% increase makes the new bar exactly twice as long. The formula line repeats the calculation with your numbers.

Results are shown with up to four decimal places. When working with money, round the final total — not the intermediate amount — to avoid small rounding drift, unless your tax authority or employer specifies otherwise.

Applying several increases

Successive increases compound. A 10% increase followed by another 10% increase is not 20% but 21%, because the second increase applies to the already-increased amount: 100 × 1.1 × 1.1 = 121. To find the combined effect of several increases, multiply their factors together. For example, three annual rent increases of 3%, 5% and 4% give 1.03 × 1.05 × 1.04 ≈ 1.1248, a total rise of about 12.5%.

You can do this with the calculator by running it once per step and using each result as the next original number.

Limits of the formula

The formula assumes the percentage applies to the original number. Some real-world figures are quoted differently: a "price including 20% VAT" means the tax is 20% of the pre-tax price, but a "20% gross margin" is a share of the selling price, which requires dividing by 0.8 rather than multiplying by 1.2. Make sure your percentage is "of the original" before using this tool.

The calculator accepts negative original numbers (the increase then moves the value further from zero in the negative direction, since the amount is computed relative to the original), but it rejects negative percentages — for a reduction, use the percentage decrease calculator. To work out what percentage a past increase was, use the percentage change calculator, and to reverse an increase (find the price before tax), divide the final value by the factor: 69.70 ÷ 1.0725 ≈ 64.99.

Common uses

Percentage increases appear everywhere money changes hands. Employers announce raises as a percentage, landlords cap rent increases at a percentage, and governments add sales tax or VAT as a percentage of the pre-tax price. Restaurants and freelancers add service charges, and retailers set selling prices by marking up wholesale costs. Outside of money, coaches plan training loads with gradual percentage increases (for example, adding no more than 10% running distance per week), and planners project population or demand growth with an annual percentage.

In each case the question is the same: "starting from this number, what do I get after adding this percentage?" — which is exactly what this calculator answers.

Common mistakes

The most frequent error is applying the percentage to the wrong base, such as calculating a raise on take-home pay when it applies to gross salary. Another is confusing an increase by a percentage with an increase to a percentage: increasing 80 by 25% gives 100, while increasing it to 125% of itself gives the same 100 — but "to 25%" would be a decrease to 20. Read the wording carefully before entering numbers.