Live demo (works without JavaScript):
Sample: 23% of 480 = 110.4 — the tool computes any percentage, percent-change or ratio.
enter values in the form → exact resultWritten by Sarah Mitchell · Reviewed by Jane Smith · July 29, 2026
Calculate percentages, increases, decreases, and proportions — three calculators in one.
Percentage problems come in three shapes, and each shape asks for a different pair of inputs. The first finds the part: what is 23 percent of 480. The second finds the whole: 92 is 40 percent of what number. The third finds the change: what percentage did 80 grow to 100. This calculator puts all three on a single page, so the same tool handles a shopping discount, a class grade, and a year-over-year report without switching tabs.
Pick the operation that matches your question. The first box takes a percentage and a value and returns the portion, useful for tips, taxes, and discounts. The second takes a portion and its percentage and works backward to the total. The third takes an old value and a new value and returns the change as a percentage, with a direction label that says increase or decrease so the sign is never ambiguous.
Start with the first operation and enter 23 for the percentage and 480 for the value. The calculator answers 110.40, because 480 split into a hundred equal parts gives 4.80 per part, and twenty-three of those parts total 110.40. The result carries two decimals, matching the standard way money is written.
Now try the change operation with 80 as the old value and 100 as the new one. The answer reads 25.00% increase, because 100 minus 80 is 20, and 20 is exactly a quarter of the original 80. Reverse the inputs and the same arithmetic returns 20.00% decrease, showing that the direction of the comparison matters.
Percent change divides by the old value, and division by zero has no answer. If the old value is entered as zero, the calculator refuses to invent a percentage and returns a clear "old value is 0" notice instead. Going from zero to any number is an infinite jump in percentage terms, so the honest response is to say the change is undefined rather than to print a misleading figure.
The two operations answer different questions, and confusing them is a classic reporting error. If an interest rate moves from 4% to 5%, the increase is one percentage point, because the rates are measured on the same scale. But the same move is a 25% rise relative to the starting rate, since 1 divided by 4 is 0.25. The change box computes the relative figure, and it is worth keeping the distinction in mind when you read the answer.
A sale that says "20% off, then an extra 10% off" is not a 30% discount, because the second reduction applies to the already-reduced price. Run the numbers through the page to see why: 20% of 100 is 20, leaving 80, and 10% of that 80 is 8, leaving 72. The change operation with 100 and 72 reports a 28.00% decrease, which is the true total saving. Two sequential cuts never add up to the sum of their percentages, and the calculator makes the real outcome visible.
The first one. Enter the discount as the percentage and the original price as the value to get the amount taken off, then subtract that portion from the price yourself to find the total you pay.
The change operation compares the new value to the old one and appends the word increase or decrease to the result, so a falling number reads as a decrease without you having to interpret a minus sign.
Because percent change divides by the old value, and zero cannot be a divisor. The page returns a clear notice in that case instead of printing a number that has no mathematical meaning.
Two. Money amounts and percentage reports conventionally use two decimal places, so the results follow that format across all three operations.
Yes, with the second operation. Enter the portion and its percentage, and the calculator works backward to the whole, which is how you recover a full bill from a known tip or a full score from a graded part.
Percentages are shorthand for hundredths, and the three operations cover the questions they create. A 7% sales tax on a 60 dollar purchase is 4.20, a student who answers 34 of 40 questions correctly has scored 85%, and a stock that falls from 200 to 150 has lost 25% of its value. Each of those is one of the three boxes, and each runs instantly in the browser without a round trip to a server.
Retailers use percentages in two ways that sound alike but measure different things. Markup is the percentage added to the cost you paid to arrive at the selling price, while margin is the percentage of the selling price that ends up as profit. A 50 percent markup on a 40 dollar cost yields a 60 dollar price, yet the margin on that sale is only 33 percent, because the profit of 20 is a third of 60.
The same arithmetic drives commissions, where a salesperson earns a percentage of what they sell, and interest rates, where a loan balance grows by a percentage each period. Tax authorities add VAT or sales tax as a percentage of the purchase, so the first box on this page settles the final price in one step.
Budgets lean on the same skills. If housing should stay near 30 percent of income, the change box tells you whether your current rent sits above or below that target, and the whole box works backward when you know your share of a bill. Even a weight goal can be expressed as a percentage of starting mass, which turns a long campaign into a single readable figure.