Percentage Calculator

About This Tool

This calculator solves the most common percentage problems in one click: finding what percent one number is of another, calculating a percentage of a number, computing percentage increase or decrease, and working backwards from a percentage to find the original value. All calculations run instantly in your browser using standard arithmetic formulas, no page reload required.

How to Use

1. Choose the type of calculation you need from the tabs, "% of number", "what % is X of Y", "% change", etc.
2. Fill in the known values in the input fields.
3. The result calculates automatically as you type.
4. Click Copy to copy the result to your clipboard.

Common Use Cases

• Working out a sale price: a $60 jacket is marked 30% off. Use "Decrease Y by X%" with Y = 60 and X = 30 to get the final price of $42 instantly, without doing the subtraction by hand.
• Splitting a restaurant tip: use "What is X% of Y?" with the bill total and a tip percentage (15, 18, or 20) to get the tip amount, then divide that plus the bill by the number of people at the table.
• Comparing month over month sales figures: use "Percentage change from X to Y" with last month's revenue as X and this month's as Y to get a signed percentage that shows growth or decline at a glance.
• Checking a test or survey score: use "X out of Y as a percentage" to convert a raw score like 42 out of 50 into a percentage grade (84%) instantly.
• Reverse-calculating an original price from a discounted one: if you know the sale price and the discount percentage, use "X is what % of Y" alongside the increase/decrease tab to work backward to the pre-discount price.

Percentage Change vs Percentage Points

These two terms are commonly confused. A percentage change is a relative measure: going from 20% to 25% is a 25% increase, because (25 minus 20) divided by 20, times 100, equals 25%. A percentage point change is an absolute measure of the same move: 20% to 25% is simply a 5 percentage point increase. News headlines about interest rates, conversion rates, or approval ratings frequently misuse these interchangeably, which can make a modest shift sound dramatic (or vice versa). The "Percentage change from X to Y" calculator above computes the relative percentage change; to get the percentage point difference, subtract the two raw percentage values directly.

Troubleshooting

• The percentage change result shows a dash instead of a number: this happens when the "From" value is exactly 0, since percentage change is undefined when dividing by zero. Enter a non-zero starting value.
• The result has too many decimal places: the calculator rounds internally to 6 decimal places and then trims trailing zeros, so a result like 33.333333% reflects a genuinely repeating fraction (for example 1 out of 3), not a display bug.
• Increase and decrease give different final values for the same X and Y: that is expected. Increasing 100 by 10% gives 110, but decreasing 110 by 10% gives 99, not 100, because the 10% is calculated against a different base value each time.
• Copy button appears to do nothing: the Copy button is disabled (no-op) until a valid result other than the placeholder dash is showing. Fill in both fields for that calculator first.

Frequently Asked Questions