Percentages: amounts, change, and ratios
Find percentages, discounts, increases, and “what percent of” in seconds.
Open Percentage CalculatorWhen this is useful
Percentage calculations look similar but answer different questions. Twenty percent of 150 is an amount: 20 × 150 ÷ 100 = 30. By contrast, asking what percent 30 is of 150 produces a ratio: 30 ÷ 150 × 100 = 20%. Choose the mode before entering numbers.
A reliable workflow
Percentage change uses the old value as its base: (new − old) ÷ old × 100. Moving from 100 to 120 is a 20% increase; returning from 120 to 100 is about a 16.67% decrease. Changes from a zero base are undefined, so this tool does not manufacture a result for that case.
Pick a calculation mode (percent of, change, or reverse). Enter your numbers. Get the answer instantly. Copy the result if needed.
What to check before you finish
For discounts, calculate the discount amount and subtract it from the original price. Be careful when comparing percentages with percentage points: a rate moving from 4% to 5% rises by one percentage point but by 25% relative to its starting value. Results use floating-point arithmetic and are not an accounting ledger.
Keep the next step simple
Open the Percentage Calculator above to try the workflow. Your input is processed in your browser, without an account or file uploads. The related tools below can help with the next step; check the output before publishing it or adding it to a production system.