What This Tool Does
This tool covers the five percentage calculations people look up most often: percent of a number, what percent one value is of a total, percent change between two values, adding or removing a percentage, and reversing a percentage back to its original total. Instead of five separate calculators, one tool handles all of them, with your numbers carried over as you switch.
How to Calculate a Percentage
Pick a formula from the tabs at the top, enter your two values, and the result updates instantly, along with a formula preview showing exactly how it was computed. The reference panel on the right shows all five formulas applied to the same two numbers at once, plus common real-world scenarios like a tip or discount calculation.
The Five Formulas Explained
"% of a number" answers questions like "what is 15% of 200". "Part of total" answers "what percent is 15 out of 200". "% change" answers "what is the percent change from 200 to 230". "Add/remove %" answers "what is 200 plus 15%" or "200 minus 15%". "Reverse %" answers "15 is 15% of what total".
Margin vs. Markup: a Common Mix-Up
Margin and markup are both computed from the same two numbers, cost and price, but they divide by different bases and are easy to confuse. Margin divides the difference by the price (revenue), markup divides the difference by the cost. For the same cost and price, markup is always a larger percentage than margin, the reference panel computes both side by side so the difference is visible directly.
Common Uses for a Percentage Calculator
Calculating a tip or discount at checkout, figuring out a percent change between two numbers like a price increase or a metric shift, working out margin or markup for pricing, and reversing a known percentage back to its original total are all common uses for this tool. It works as a percent change calculator, a reverse percentage calculator, a discount calculator, a percentage increase calculator and percentage decrease calculator, a tip calculator percentage, a margin vs markup calculator, a percent of number calculator, and a percentage difference calculator all in one place.