Percentage Calculator — Tips & Guide
Calculate percentages instantly for discounts, tips, tax, grade scores, growth rates, and more. Four calculation modes cover every common percentage problem.
Calculate Discounts
Use "% of a Number" to find discount amounts. Enter the discount percentage and the original price to see exactly how much you save and the final price.
Track Growth Rates
Use "% Change" to calculate revenue growth, follower increases, or weight loss progress. Enter the old value and new value to see the exact percentage change.
Score Grades
Use "What % is X of Y?" to convert a raw score to a percentage — for example, 42 out of 50 = 84%. Works for any ratio where you need to express one number as a percentage of another.
Reverse-Calculate Totals
If you know a percentage amount and need the original total (e.g., a 20% VAT amount of £40 → original price), use the "Find Total" mode to reverse-engineer the base value.
Calculate Tips
To calculate a restaurant tip: use "% of a Number," enter your tip percentage (15%, 18%, 20%) and your bill total. The result is your tip amount — add it to the bill for the total.
Tax Calculations
Add sales tax by calculating "X% of price" and adding it to the price, or use "Find Total" if you only know the tax amount and rate to find the pre-tax price.
To find what percentage one number is of another: divide the part by the whole and multiply by 100. Example: 30 is what percent of 120? — 30 ÷ 120 × 100 = 25%. To find a percentage of a number: multiply the number by the percentage and divide by 100. Example: 15% of 80 — 80 × 15 ÷ 100 = 12. This calculator handles all these calculations automatically.
Percentage increase = ((New Value − Old Value) ÷ Old Value) × 100. If a stock rises from $50 to $65, the increase is ((65−50) ÷ 50) × 100 = 30%. Percentage decrease works the same formula — if the new value is lower than the old value, the result is negative, representing a decrease. This is useful for tracking price changes, revenue growth, follower counts, and weight change.
Divide X by Y and multiply by 100. Example: what percent is 45 of 180? — 45 ÷ 180 × 100 = 25%. This is the formula for converting a raw score to a grade percentage, expressing a part of a budget as a percentage of the total, or finding what fraction of a goal you've achieved.
A percentage expresses a ratio as a fraction of 100 — for example, scoring 85% on a test means you answered 85 out of 100 questions correctly. A percentile ranks your score relative to others — being in the 85th percentile means you scored higher than 85% of other test-takers. Percentages are absolute measurements; percentiles are relative rankings. Both use the % symbol but measure very different things.