Percentage Calculator
Discounts, share of a total, percent change — pick your question type.
e.g. "30 is what % of 120" → 25%; "25% of 120" → 30; "from 100 to 130" → up 30%.
What is a percentage?
A percentage expresses a number as a fraction of 100, using the % symbol. It's the standard way to compare quantities that have different bases — discounts, interest rates, growth rates, and survey results are almost always shown as percentages because they put everything on the same 0-100 scale.
How do you calculate a percentage?
The three most common percentage questions each use a slightly different formula:
For example, to find out how much you saved on a discount, you're really working backwards from the "percent of" formula; to find out how much a metric grew, you're using the "percent change" formula. This tool builds all three into separate modes so you don't have to remember which formula to use.
Frequently asked questions
How do I calculate the price after a discount?
Multiply the original price by the discount rate as a decimal — for a 20% off sale, multiply by 0.80 (100% − 20%) to get the discounted price directly. You can also use this tool's "A% of B" mode: set A to 80 and B to the original price.
Can a percentage be more than 100%?
Yes. Whenever a value more than doubles, the percent change exceeds 100% — for example, revenue growing from $100k to $250k is a 150% increase. There's no upper limit on percentages; only "share of a whole" scenarios are naturally capped at 100%.
Is a "percentage point" the same as a percentage?
No, and the two are frequently confused. If an interest rate rises from 5% to 8%, that's a 3 percentage point increase — but expressed as a percentage change, it's a 60% increase (3 ÷ 5). News reports on rates and unemployment usually mean percentage points, so it's worth checking which one is meant before doing the math.
Related Tools
📖 Related guide
Learn the difference between a percentage of a value and a percentage change before comparing numbers.
Read the percentage guide →How to check a percentage result
Percentage pitfalls
A 20% discount means multiply by 0.8, not subtract 20 from the price as if it were a fixed amount in every currency context. A +10% change followed by a −10% change does not return to the original value—apply factors in sequence.
Use this tool to check discounts, proportions, and relative change quickly. For official tax or contract math, follow the rules in the governing document.