Percentage Calculator
Calculate percentages, increases, decreases, and percentage changes.
What is the Percentage Calculator?
The Percentage Calculator is a free browser tool that works out percentage relationships between numbers, including what percent one value is of another, the result of adding or subtracting a percentage, and the percent change from one value to a new one.
You enter up to three numbers (a value, a total, and a percentage) and the calculator updates four results live as you type: percentage of total, value increased by the percentage, value decreased by the percentage, and the percentage change from the value to the total.
Every calculation runs entirely in your browser using standard arithmetic formulas. There is no signup, and nothing you type is sent to a server.
How to use the Percentage Calculator
- 1Enter a number in the Value field, which acts as the base for increase, decrease, and percent-change results.
- 2Enter a number in the Total field to compute what percentage the Value is of that Total.
- 3Enter a number in the Percentage field to apply a percentage increase and decrease to the Value.
- 4Read the four result cards: percentage of total, value plus the percentage, value minus the percentage, and percent change from Value to Total.
- 5Pick one of the example presets (such as tax, discount, or growth) to load sample numbers and see how each result is derived.
- 6Press Ctrl+L (or Cmd+L) to clear every field and start a fresh calculation.
What you can use it for
- Calculating sales tax or VAT on top of a base price during checkout flow testing.
- Working out a discounted price when applying a percent-off promotion.
- Measuring growth between two figures, such as month-over-month signups or revenue.
- Checking profit margin by finding what percentage one amount is of a larger total.
- Verifying percentage values in spreadsheets or analytics dashboards without opening a spreadsheet app.
- Estimating tip amounts or splitting a percentage-based fee across a total.
Key features
- Four results computed at once: percentage of total, increase, decrease, and percent change.
- Live recalculation that updates every result card as you edit any input.
- Built-in example presets for tax, discount, growth, and profit-margin scenarios.
- Keyboard shortcut (Ctrl+L) to clear all fields instantly.
- Results rounded to two decimal places for readable, consistent output.
Frequently asked questions
How do I calculate what percentage one number is of another?
Enter the part as the Value and the whole as the Total. The calculator divides Value by Total, multiplies by 100, and shows the result in the percentage-of card. For example, 25 as the Value and 200 as the Total returns 12.50%.
How do I calculate a percentage increase or decrease?
Put the starting number in the Value field and the percentage in the Percentage field. The tool shows Value multiplied by (1 + percentage/100) for the increase and (1 - percentage/100) for the decrease, so 100 with 20% gives 120 and 80.
What formula does the percent change calculation use?
Percent change is calculated as ((Total - Value) / Value) x 100, where Value is treated as the original number and Total as the new number. A positive result means growth and a negative result means a decline.
Is the percentage calculator free to use?
Yes. The percentage calculator is completely free, requires no account, and runs entirely in your browser. None of the numbers you enter are transmitted or stored on a server.
Why are my results showing a dash instead of a number?
A result card shows a dash when the inputs it needs are missing or invalid. Percentage-of and percent change also require the divisor to be non-zero, so a Total of 0 or a Value of 0 will leave the related result blank.
How many decimal places does the percentage calculator show?
All results are rounded to two decimal places. This keeps percentage and currency-style outputs readable while still being precise enough for tax, discount, and margin calculations.