Percentage tools
All the percentage calculators and explainers in one place.
Average Percentage Calculator
Find the simple average of multiple percentages. Add rows and get the mean percentage with a clear breakdown.
Open tool →Cumulative Percentage Calculator
Add values in order and see cumulative percentages as you go. Perfect for data analysis and Pareto charts.
Open tool →Decimal to Percentage Calculator
Convert any decimal to a percentage instantly. Simple input, clear answer and worked examples.
Open tool →Discount Calculator
Work out price after discount, savings, and discount percent. Enter any two values and get the rest instantly.
Open tool →Fraction to Percentage Calculator
Convert any fraction to a percentage. Supports mixed numbers and improper fractions with clear steps.
Open tool →Percent Error Calculator
Calculate percent error from a measured value and a true value. Shows absolute percent error and signed error with clear steps.
Open tool →Percentage Allocation Calculator
Split a total amount by percentages. Add rows and see each allocated share with a running check to 100%.
Open tool →Percentage Change Calculator
Work out the percentage change between two numbers. Handles both increases and decreases with clear steps.
Open tool →Percentage Composition Calculator
Break down a set of values into percentages of the total. See each share clearly with a 100% check.
Open tool →Percentage Decrease Calculator
Work out the percentage decrease between two numbers with a clear answer and simple steps.
Open tool →Percentage Decrease Needed Calculator
Find the percentage decrease needed to go from a current value to a lower target value.
Open tool →Percentage Difference Calculator
Compare two numbers and get the percentage difference. Uses the average of the two values for a fair comparison.
Open tool →Percentage Increase Calculator
Work out the percentage increase between two numbers quickly and clearly with steps explained.
Open tool →Percentage Increase Needed Calculator
Find the percentage increase needed to go from a current value to a target value.
Open tool →Percentage of a Number Calculator
Work out what X percent of a number is. Enter a percentage and a value to get an instant result with clear steps.
Open tool →Percentage of Total Calculator
Enter a part and a total to see what percentage the part represents. Clear result with a short explanation.
Open tool →Percentage Proportion Calculator
Split an amount into parts by chosen percentages. See each portion in clear figures with a check to 100%.
Open tool →Percentage to Decimal Calculator
Convert any percentage to a decimal number instantly. Simple input, clear result and worked examples.
Open tool →Percentage to Fraction Calculator
Convert any percentage to a simplified fraction in lowest terms. Supports decimals and shows working.
Open tool →Percentage to Permille Calculator
Convert percentages into permille (‰ per thousand) instantly. Clear input, clean result and worked examples.
Open tool →Percentage to Ratio Calculator
Convert a list of percentages into a simplified ratio. Keeps proportions and reduces to whole numbers.
Open tool →Ratio to Percentage Calculator
Convert a ratio like 3:4 or 2:5 into percentages for each part. Clean results with totals checked to 100%.
Open tool →Reverse Percentage Calculator
Work backwards from a final price to find the original before a percentage increase or discount.
Open tool →Weighted Percentage Calculator
Calculate a weighted percentage from multiple values and weights. Great for grades, budgets and scoring.
Open tool →What Percent is X of Y Calculator
Find out what percent one number is of another. Enter X and Y to get the percentage instantly with a clear explanation.
Open tool →Work with percentages without the faff
This section is for quick answers. Each calculator is built to be fast, readable and accurate. If you know the numbers, you can get a result in seconds. If you want a refresher, every tool includes a short explanation and a worked example so you can see the method in plain English. Prices, margins, discounts and growth all rely on percentage thinking, yet most people only use it when they have to. The aim here is to make it effortless, so you can check a rise or fall, compare deals, or sense-check a claim without opening a spreadsheet.
Tools will grow over time. Expect the essentials like increase and decrease, VAT, profit margin, gross to net and common conversions. Each page keeps the layout clean so there is no hunting for inputs or results. Bookmark this hub if you work with numbers often. If there is a calculator you would like to see, send a request and it will be prioritised based on demand. Stable Numbers is a resource first. It is here to save time, cut errors and give you confidence in the result.