Percentage Calculator
By Miikka · CalcBrew · Updated
The percentage calculator finds a percentage of a number, the percentage change, and increases or decreases. Percent means hundredth (% = /100).
How the calculator works and what it’s for▾
The most common calculations
Percentage of a number: X% of Y = Y × X/100. E.g. 20% of 150 = 30.
What percent X is of Y = X / Y × 100. Percentage change = (new − old) / old × 100.
Percent vs percentage point
These are often confused. If a rate rises from 5% to 7%, that’s a 2 percentage-point rise but a 40% relative increase. Use the right term especially with interest rates and vote shares.
Example
A product costs $80 with a 25% discount: discount $20, final price $60. If a price rises from $60 to $75, the increase is 25%.
Tips
Successive discounts don’t add up: 30% + 20% is not 50% but 44% (the second applies to the already discounted price). An increase followed by the same-percent decrease does not return to the original price.
🔄 Reviewed June 2026
The five percentage questions and how to solve them
| Question | Formula | Example |
|---|---|---|
| What is P% of X? | X × P ÷ 100 | 20% tip on an $85 check: 85 × 0.20 = $17.00 |
| X is what percent of Y? | X ÷ Y × 100 | 45 correct out of 60: 45 ÷ 60 = 75% |
| X is P% of what number? | X ÷ (P ÷ 100) | $30 is 15% of 30 ÷ 0.15 = $200 |
| Percent change from A to B | (B − A) ÷ A × 100 | $50 to $65: 15 ÷ 50 = +30% |
| Increase or decrease X by P% | X × (1 ± P ÷ 100) | $1,200 rent up 4%: 1,200 × 1.04 = $1,248 |
Percent change, percentage points and percent difference
Percent change is measured from the starting value: a rent increase from $1,500 to $1,650 is (1,650 − 1,500) ÷ 1,500 = 10%. The same $150 drop from $1,650 back to $1,500 is only a 9.1% decrease, because the base is larger. This is also why a 50% loss needs a 100% gain to recover.
Percentage points compare two percentages by subtraction. A mortgage rate that moves from 6% to 7% rises by 1 percentage point, but by 16.7% in relative terms. News about interest rates, poll results and tax rates usually means points.
Percent difference has no starting value: it divides the gap by the average of the two numbers. Between 40 and 60 the difference is 20 ÷ 50 = 40%, whichever comes first. Use it to compare two quotes or two measurements.
Reverse percentages: sale prices and sales tax
To undo a percentage, divide instead of multiplying. A jacket marked $84 after 30% off cost 84 ÷ 0.70 = $120 before the sale. A receipt that totals $107 with 7% sales tax was 107 ÷ 1.07 = $100 before tax. Subtracting the percentage from the final amount (84 − 30% = $58.80) gives the wrong answer, because the 30% was taken from the original price, not the reduced one.
For everyday cases there are dedicated tools: the tip calculator splits a restaurant bill, and the discount calculator stacks a sale and a coupon in the right order.
Percentages in your head
Move the decimal point one place to the left for 10% ($68 → $6.80), halve that for 5% ($3.40), and add the two for 15% ($10.20). Double 10% for 20%, and remember that x% of y equals y% of x: 8% of 50 is the same as 50% of 8, which is 4.
| Amount | 5% | 10% | 15% | 20% | 25% |
|---|---|---|---|---|---|
| $20 | $1.00 | $2.00 | $3.00 | $4.00 | $5.00 |
| $45 | $2.25 | $4.50 | $6.75 | $9.00 | $11.25 |
| $60 | $3.00 | $6.00 | $9.00 | $12.00 | $15.00 |
| $80 | $4.00 | $8.00 | $12.00 | $16.00 | $20.00 |
| $100 | $5.00 | $10.00 | $15.00 | $20.00 | $25.00 |
| $150 | $7.50 | $15.00 | $22.50 | $30.00 | $37.50 |
| $250 | $12.50 | $25.00 | $37.50 | $50.00 | $62.50 |
Frequently asked questions
Cite this calculator
CalcBrew. (2026). Percentage Calculator. https://calcbrew.com/percentage-calculator“Percentage Calculator.” CalcBrew, 2026, calcbrew.com/percentage-calculator.Link to https://calcbrew.com/percentage-calculator. Results are estimates; cite the underlying formula or data source for academic work.
Related tools
More in Math & Statistics · All calculators