Percentage Calculator
Calculate percentages quickly and accurately. Find percentage values, increases, decreases, or comparisons between numbers in seconds. Ideal for finance, education, shopping, and everyday math. Free, fast, and easy to use.
Percentage Calculator
The Percentage Calculator solves 15 different types of percentage problems. Select the formula type from the dropdown that matches your question, enter the known values, click Calculate, and the result is returned immediately. The 15 formulas cover every common percentage calculation: finding a percentage of a number, expressing one number as a percentage of another, calculating percentage increases and decreases, and reversing percentage operations to find the original value before a percentage was applied.
Percentage calculations appear in almost every area of everyday and professional life: prices and discounts, taxes and VAT, interest rates, test scores, salary changes, statistics, and measurement comparisons. The breadth of formula types in this tool means you can solve the problem as it is stated — rather than having to rearrange the question to fit a single-formula calculator.
How to use the Percentage Calculator
- From the Formula dropdown, select the formula type that matches your question. The 15 options are organized below by category — see the formula reference table for guidance on which to choose.
- Enter the known values in the fields that appear. Different formula types require different inputs — the fields update to match the selected formula.
- Click Calculate.
- Read the result. The calculation is instant.
The most common reason for a wrong answer is selecting the wrong formula type. Read the formula label carefully — 'What is P% of X?' and 'P% of X is what?' are the same calculation, while 'X plus P% is what?' and 'What plus P% is Y?' are different. If your result seems wrong, check that the formula you selected matches the question you are answering. The formula reference table below explains every type with a worked example.
All 15 formulas — what each one calculates
The dropdown contains 15 formula types organized in four groups. The table below explains what each formula calculates, provides the underlying formula, and gives a worked example with a real-world use case:
| Formula (dropdown label) | Calculation | Example and use case |
| Basic percentage operations | ||
| What is P% of X? | Result = X × (P ÷ 100) | What is 20% of 250? → 250 × 0.20 = 50. Use for: applying a discount rate to a price, calculating a tip, finding the tax amount on a subtotal. |
| Y is what% of X? | Result = (Y ÷ X) × 100 | 15 is what% of 60? → (15 ÷ 60) × 100 = 25%. Use for: finding the percentage score on a test, calculating market share, comparing two quantities. |
| Y is P% of what? | Result = Y ÷ (P ÷ 100) | 30 is 15% of what? → 30 ÷ 0.15 = 200. Use for: finding the original price before a percentage was applied, recovering the base value from a known portion. |
| What% of X is Y? | Result = (Y ÷ X) × 100 | What% of 80 is 20? → (20 ÷ 80) × 100 = 25%. Functionally the same as 'Y is what% of X' — the phrasing makes it easier to match your specific question to the right formula. |
| P% of what is Y? | Result = Y ÷ (P ÷ 100) | 25% of what is 50? → 50 ÷ 0.25 = 200. Use for: reverse-calculating the whole from a known fraction, finding an original total from a percentage portion. |
| P% of X is what? | Result = X × (P ÷ 100) | 15% of 340 is what? → 340 × 0.15 = 51. Same calculation as 'What is P% of X' with different phrasing — choose whichever matches your question. |
| Fraction and ratio formulas | ||
| Y out of what is P%? | Result = Y ÷ (P ÷ 100) | 12 out of what is 40%? → 12 ÷ 0.40 = 30. Use for: finding the total when you know a part and the percentage that part represents. Example: 12 correct answers represent 40% of the test — how many questions total? |
| What out of X is P%? | Result = X × (P ÷ 100) | What out of 50 is 30%? → 50 × 0.30 = 15. Use for: finding the specific count that represents a given percentage of a total. Example: 30% of a 50-student class passed — how many students? |
| Y out of X is what%? | Result = (Y ÷ X) × 100 | 18 out of 24 is what%? → (18 ÷ 24) × 100 = 75%. Use for: calculating pass rates, attendance percentages, success rates, and fraction-to-percentage conversions. |
| Percentage increase (adding a percentage) | ||
| X plus P% is what? | Result = X × (1 + P ÷ 100) | 200 plus 15% is what? → 200 × 1.15 = 230. Use for: adding VAT or sales tax to a price, calculating a salary after a raise, finding the total after a percentage increase. |
| X plus what% is Y? | Result % = ((Y − X) ÷ X) × 100 | 200 plus what% is 250? → ((250 − 200) ÷ 200) × 100 = 25%. Use for: finding the percentage increase between two values, calculating the raise percentage when you know the before and after amounts. |
| What plus P% is Y? | Result = Y ÷ (1 + P ÷ 100) | What plus 20% is 120? → 120 ÷ 1.20 = 100. Use for: reverse-calculating the original price before tax was added. If the tax-inclusive price is £120 with 20% VAT, the ex-VAT price was £100. |
| Percentage decrease (subtracting a percentage) | ||
| X minus P% is what? | Result = X × (1 − P ÷ 100) | 500 minus 30% is what? → 500 × 0.70 = 350. Use for: applying a discount to a price, calculating a value after depreciation, finding the remaining amount after a reduction. |
| X minus what% is Y? | Result % = ((X − Y) ÷ X) × 100 | 500 minus what% is 350? → ((500 − 350) ÷ 500) × 100 = 30%. Use for: finding the discount percentage applied when you know the original and discounted prices. |
| What minus P% is Y? | Result = Y ÷ (1 − P ÷ 100) | What minus 25% is 75? → 75 ÷ 0.75 = 100. Use for: reverse-calculating the original price before a discount. If the sale price is £75 after a 25% discount, the original price was £100. |
Common use cases — which formula to use
Calculating a discount on a price
Use 'X minus P% is what?' — enter the original price as X and the discount percentage as P. The result is the discounted price. Example: £200 product with a 15% discount → 200 minus 15% = £170. To find the original price from the discounted price: use 'What minus P% is Y?' — enter the sale price as Y and the discount percentage as P. The result is the original pre-discount price.
Adding VAT or sales tax
Use 'X plus P% is what?' — enter the net (ex-tax) price as X and the tax rate as P. The result is the total including tax. Example: £100 plus 20% VAT = £120. To find the net price from the tax-inclusive total: use 'What plus P% is Y?' — enter the tax-inclusive price as Y and the VAT rate as P. The result is the ex-VAT amount. Example: £120 including 20% VAT → what plus 20% is 120 → £100 net.
Calculating a percentage increase or decrease between two values
Use 'X plus what% is Y?' for an increase (when Y is larger than X). Enter the starting value as X and the ending value as Y. The result is the percentage increase. Use 'X minus what% is Y?' for a decrease (when Y is smaller than X). Enter the original value as X and the reduced value as Y. The result is the percentage decrease. Example: salary increased from £30,000 to £33,000 → 30000 plus what% is 33000 → 10% increase.
Expressing a test score as a percentage
Use 'Y out of X is what%?' — enter the score as Y and the total marks available as X. The result is the percentage score. Example: 42 out of 60 marks → (42 ÷ 60) × 100 = 70%.
The reverse discount formula ('What minus P% is Y?') is the most commonly needed but least obvious calculation in everyday use. If a sale price is shown and you want to know what the original price was before the discount, this is the formula. Many people incorrectly try to add the discount percentage back to the sale price — this gives the wrong answer because the percentage was calculated on the original price, not the sale price. Example: a 25% discount produces a sale price of £75. Adding 25% to £75 gives £93.75, not £100. The correct calculation is: 75 ÷ (1 − 0.25) = 75 ÷ 0.75 = £100.
Usage limits
| Account type | Daily calculations |
| Guest | 25 per day |
| Registered | 100 per day |
Related tools
- Average Calculator — calculate the mean of a set of numbers. Use alongside the percentage calculator when working with average rates, average percentages, or mean values across groups.
- Discount Calculator — dedicated tool for calculating sale prices and savings from discount percentages.
- Sales Tax Calculator — dedicated tool for adding and removing sales tax and VAT from prices.
- Probability Calculator — calculate odds and likelihoods. Probabilities are closely related to percentages for statistical analysis.
Frequently asked questions
What percentage formulas does this calculator support?
The calculator supports 15 distinct percentage formula types across four categories: basic percentage operations (finding X% of a number, expressing one number as a percentage of another, and finding the whole from a known percentage), fraction and ratio formulas (converting between fractions and percentages), percentage increase formulas (adding a percentage and reversing the operation), and percentage decrease formulas (subtracting a percentage and reversing the operation). The formula reference table above lists every type with its formula and a worked example.
How do I calculate a percentage increase?
Select 'X plus what% is Y?' from the dropdown. Enter the original (lower) value as X and the new (higher) value as Y. The result is the percentage increase. The formula is: ((Y − X) ÷ X) × 100. Example: a price increased from 80 to 100 → (100 − 80) ÷ 80 × 100 = 25% increase. For a percentage decrease (when the new value is lower), use 'X minus what% is Y?' with the original as X and the reduced value as Y.
How do I find the original price before a discount was applied?
Use 'What minus P% is Y?' — enter the sale (discounted) price as Y and the discount percentage as P. The result is the original price. The formula is: Y ÷ (1 − P/100). Example: a sale price of £75 with a 25% discount was originally: 75 ÷ 0.75 = £100. A common mistake is to add the discount percentage back to the sale price — this gives the wrong answer because the percentage was applied to the original price, not the sale price.
How do I find the price before VAT was added?
Use 'What plus P% is Y?' — enter the tax-inclusive total as Y and the VAT rate as P. The result is the ex-VAT (net) price. The formula is: Y ÷ (1 + P/100). Example: a VAT-inclusive price of £120 at 20% VAT → 120 ÷ 1.20 = £100 net. To add VAT to a net price, use 'X plus P% is what?' — enter the net price as X and the VAT rate as P.
What is the difference between 'What is P% of X?' and 'P% of what is Y?'
They solve different unknowns. 'What is P% of X?' finds the result when you know the percentage and the total — the unknown is the percentage value (e.g. what is 20% of 250? = 50). 'P% of what is Y?' finds the total when you know the percentage and the result — the unknown is the whole (e.g. 20% of what is 50? = 250). They are inverse operations of each other: the first multiplies, the second divides.
How do I calculate a percentage score for a test?
Use 'Y out of X is what%?' — enter the marks scored as Y and the total marks available as X. The result is the percentage. Example: scoring 36 out of 45 marks → (36 ÷ 45) × 100 = 80%. If you want to find how many marks correspond to a specific percentage: use 'What out of X is P%?' — enter the total marks as X and the target percentage as P.
Can I use this for financial calculations like interest and profit margins?
Yes. All 15 formula types are applicable to financial calculations. For simple interest on a loan or savings amount: 'What is P% of X?' (where X is the principal and P is the annual interest rate) gives the annual interest amount. For profit margin: 'Y out of X is what%?' (where Y is the profit and X is the revenue) gives the profit margin percentage. For markup: use the percentage increase formulas. For reverse-calculating the base from a marked-up price: use the increase reversal formula 'What plus P% is Y?'.
Is the Percentage Calculator free?
Yes. The calculator is free within the daily usage limits shown above. Guest users can perform 25 calculations per day without creating an account. Registering a free ToolsPiNG account increases the daily limit to 100 calculations per day.