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Percentage Calculator
The three everyday percentage questions — what is X% of Y, X is what percent of Y, and the percent change between two numbers — answered instantly in one place.
Open the free Percentage Calculator →How it works
Most real-world percentage questions come in just three shapes, and each one uses a single short formula. This calculator handles all three so you never have to remember which is which.
- X% of Y — convert the percent to a decimal (divide by 100) and multiply: (X / 100) × Y. This is how you work out a tip, a commission, a deposit, or a tax amount.
- X is what percent of Y — divide the part by the whole and multiply by 100: (X / Y) × 100. Use this to express a score, a deposit, or a line item as a share of a total.
- Percent increase or decrease — take the difference, divide by the starting value, multiply by 100: (new − old) / old × 100. A positive answer is a rise; a negative answer is a drop.
A handy shortcut for a "percent off" price: multiply the original by (1 − discount%). A 20% discount means you pay 80% of the price, so just multiply by 0.80.
Worked example
Say you invoiced a client $2,400 last month and $3,000 this month, and you want to answer a few quick questions:
- What is 15% of $3,000? — 0.15 × 3,000 = $450 (for example, the amount you set aside for tax).
- $450 is what percent of $3,000? — 450 / 3,000 = 0.15, × 100 = 15%.
- What is the percent increase from $2,400 to $3,000? — (3,000 − 2,400) / 2,400 = 600 / 2,400 = 0.25, × 100 = a 25% increase.
If instead you offered that $3,000 client a 20% discount, they would pay 3,000 × 0.80 = $2,400, saving $600.
Frequently asked questions
- How do I calculate what percent of a number something is?
- To find what percent X is of Y, divide X by Y and multiply by 100. For example, 30 is what percent of 120? 30 / 120 = 0.25, and 0.25 × 100 = 25%. So 30 is 25% of 120.
- How do I calculate X percent of a number?
- Convert the percent to a decimal by dividing by 100, then multiply by the number. For example, 15% of 80 is 0.15 × 80 = 12. The same works for tips, discounts, and commissions.
- How do I calculate percentage increase or decrease?
- Subtract the old value from the new value, divide by the old value, then multiply by 100: (new − old) / old × 100. A positive result is an increase; a negative result is a decrease. For example, from 200 to 250: (250 − 200) / 200 = 0.25, or a 25% increase.
- How do I work out a percent off / discount price?
- Multiply the original price by the discount percent as a decimal to get the amount saved, then subtract it. For a 20% discount on $50: 0.20 × 50 = $10 off, so you pay $40. You can also multiply by (1 − 0.20) = 0.80 to get $40 directly.
- Why is percentage change different from percentage points?
- Percentage change measures the relative change between two numbers, while percentage points measure the absolute difference between two percentages. Going from 10% to 15% is a 5 percentage-point rise, but a 50% percentage increase (5 / 10 × 100).
- Is this percentage calculator free and private?
- Yes. The calculator is free with no sign-up, and every calculation runs entirely in your browser. No numbers you enter are uploaded or stored anywhere.