Completely FREE percentage calculator. No signup, instant answers. Handle the three percentage questions that actually come up: what is X% of Y, X is what percent of Y, and the percent change between two numbers. Pick a mode, type your numbers, and the answer updates as you type.
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The three percentage questions
Almost every real percentage problem is one of three shapes, and this calculator has a mode for each. "What is X% of Y" is for taking a portion of something — a 20% tip on a $60 bill, 15% off a price, 8.25% sales tax on a purchase. "X is what percent of Y" runs the other direction: you have two amounts and want the ratio — 45 correct answers out of 60 questions is a 75% score, $320 spent out of a $2,000 budget is 16%. "Percent change from X to Y" measures how much something grew or shrank — a salary going from $52,000 to $58,000 is an 11.5% raise, a stock dropping from $90 to $72 is a 20% decline.
The formulas, so you can check the work
None of this is mysterious, and it helps to see the arithmetic behind each mode. X% of Y is simply (X ÷ 100) × Y. To find what percent X is of Y, you compute (X ÷ Y) × 100. Percent change is (new − old) ÷ |old| × 100, where a positive result is an increase and a negative one is a decrease. The calculator uses the absolute value of the starting number in the denominator so that changes from negative starting values still read sensibly.
Percentage points vs. percent — a common trap
One distinction trips people up constantly: the difference between a percent change and a change in percentage points. If an interest rate rises from 4% to 5%, that is a one percentage point increase, but a 25% relative increase (one is one-quarter of four). News headlines routinely blur these, and the gap matters when the numbers are about rates, shares, or probabilities. When you specifically want the relative change between two rates, the percent-change mode gives it to you; when you just want the gap, subtract the two directly.
Everyday places this comes up
Discounts and sale prices, tip and tax, test and quiz scores, commission and markup, tracking a budget line against its cap, comparing this month's number to last month's, working out a raise or a rent increase, and figuring out how much a value has grown over a year. The percent-change mode in particular is the quiet workhorse — any time you find yourself saying "that went up by how much?" it has the answer.
Runs entirely in your browser
Like everything on this site, the math happens in your browser as you type. Nothing you enter is sent anywhere, there is no calculate-and-wait, and there is no account to make. For a related everyday number, the Tip Calculator handles bill splitting, and the Profit Margin Calculator covers margin and markup, which are percentage calculations with business-specific framing.
Frequently asked questions
How do I calculate what percent one number is of another?
Use the "X is what percent of Y" mode: enter the part as X and the whole as Y. The tool divides X by Y and multiplies by 100. For example, 30 out of 40 is 75%.
How do I work out a percentage increase?
Use the "percent change" mode with the original value as X and the new value as Y. A result with a plus sign is an increase; a minus sign is a decrease. Going from 50 to 65 shows +30%.
What is the difference between percent change and percentage points?
Percentage points are the plain difference between two percentages (5% − 4% = 1 point). Percent change is that difference relative to the starting value (1 ÷ 4 = 25%). Use percent-change mode for the relative figure; subtract directly for the point gap.
Important
This tool provides estimates and general-purpose documents, not financial, tax, legal, or professional advice. Verify important results before relying on them.
Support
Problem with this tool or suggestions for improvement? Please email support@niftyutilities.com.