Free Percentage Calculator Online

Find X% of a number, calculate percentage increase or decrease, or solve for the original number — four calculation modes in one tool.

Select a calculation mode and enter your numbers
Please enter valid numbers (the base value can't be zero).
Your result will appear here
PercentValue

Percentage Calculation Tips

01To find a discount price, calculate the discount amount first using "X% of Y", then subtract it from the original price.
02For GST or sales tax, use "X% of Y" with the tax rate and pre-tax amount, then add the result to get the final price.
03Exam or test scores are a "X is what % of Y" calculation — marks obtained as X, total marks as Y.
04Percentage increase and percentage points are not the same thing — going from 20% to 25% is 5 percentage points, but a 25% relative increase.
05Use "Find Original Number" when you know a discounted or taxed amount and need to work backward to the starting figure.

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Features

✓Four calculation modes in one tool
✓Find X% of any number
✓Find what percent one number is of another
✓Percentage increase and decrease with automatic labeling
✓Reverse-solve for the original number
✓Quick shortcuts for tips, GST, and discounts
✓Dynamic quick reference table
✓Instant calculation as you type
✓No sign-up, no data stored
✓Fully responsive on any device

A Percentage Calculator That Covers Every Common Case

Percentage questions come in more shapes than most calculators handle. Sometimes you need to know what 18% of an invoice total is; sometimes you have two numbers and need to know the percentage relationship between them; sometimes you're comparing an old figure to a new one and want to know whether it went up or down and by how much; and sometimes you're working backward from a final number to figure out what the original amount must have been. ToolPlex's free percentage calculator covers all four of these cases in a single tool, switchable with one click.

Finding a Percentage of a Number

This is the most common percentage calculation — figuring out a tip, a discount, a tax amount, or a commission. The formula is straightforward: divide the percentage by 100 and multiply by the number. This tool's "X% of Y" mode handles it instantly and also shows a quick reference table of common percentages of the same base number, useful for comparing a few tip or discount options at once.

Finding What Percent One Number Is of Another

This mode answers questions like "what percentage of my income is rent" or "what percentage did I score on this test." It divides the first number by the second and multiplies by 100, and is one of the most frequently searched percentage calculations, especially around exam results and budgeting.

Percentage Increase and Decrease

Comparing an old value to a new one — a price change, a salary raise, a population figure — requires a slightly different formula: the difference between the two values divided by the original value, multiplied by 100. This calculator labels the result as an increase or decrease automatically, and it's worth remembering that percentage change is relative to the starting value, which is why a 50% drop followed by a 50% rise does not bring you back to where you started.

Reverse Percentage: Finding the Original Number

Sometimes you're given the result of a percentage calculation and need to work backward — for example, knowing that a discounted price is 80% of the original and wanting to find that original price. This mode divides the known value by the percentage expressed as a decimal, solving for the starting number rather than the result.

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Frequently Asked Questions