Percent of a Number
Multiply the percentage by the base value and divide by 100. result = (percentage × base) / 100
Math
About Percentage Calculator
Live percentage math inside a luminous glass workspace for formula, change, difference, marks, money, tips, discounts, and spreadsheet use.
About this calculator
What this does
Solves nine common percentage problems in one tool: percent of a number, what percent one number is of another, percentage increase or decrease, percentage difference between two values, percentage point changes, reverse percentage calculations, discount amounts, tip and tax totals, and exam mark percentages.
Who it is for
Students working on math homework, professionals calculating discounts or tax, teachers grading assignments, shoppers figuring out sale prices, and anyone who needs quick percentage answers without memorizing formulas.
How it works
Each mode uses the standard percentage formula appropriate for that calculation. For example, percent of a number uses (percentage / 100) x base value, while percentage change uses ((new - old) / old) x 100. Results update live as you type, and each mode shows the formula used so you can verify the math or replicate it in Excel.
Limitations
All calculations are exact to two decimal places. The difference mode compares two values against their average, not a starting point. Percentage point changes are shown as the arithmetic difference between two percentages, distinct from a relative percentage change.
Formula
Percentage Change
Find the relative difference between an old and new value. change = ((new − old) / old) × 100
Percentage Difference
Compare two values against their average rather than a starting point. difference = (|a − b| / ((a + b) / 2)) × 100
Reverse Percentage
Find the original value before a percentage change. original = final / (1 + percent / 100)
How it works
Step 1
Choose a mode
Select one of nine modes from the sidebar: percent of, what percent, increase or decrease, difference, percentage points, reverse change, discount, tip or tax, or exam marks.
Step 2
Enter your values
Type numbers into the primary and secondary input fields. The label above each field changes to describe the value expected for the selected mode.
Step 3
Read the result
The calculated value appears instantly in the large result panel. The formula, Excel equivalent, and Google Sheets equivalent are displayed below for verification.
Step 4
Adjust inputs at any time
Change either value and the result updates live. Use the mode buttons in the sidebar to switch to a different calculation type.
Step 5
Share your calculation
Click CSV_SHARE to copy a URL with your current mode and values, or PRNT_OUT to send the page to a printer.
Reference ranges
Percent Of
Common uses range from 5% (small sales tax) to 25% (tip). Discounts typically fall between 10% and 50% off the original price.
Increase or Decrease
Single-digit percentage changes are normal for daily price shifts. Double-digit changes indicate significant movement, such as an 80% to 100% increase for a stock doubling.
Difference
Values under 10% mean two numbers are close relative to their average. Over 50% means they are far apart. The result is always positive because it measures symmetric distance.
Percentage Points
A move from 35% to 40% is a 5 percentage point change, which is very different from a 14.3% relative increase. This mode clarifies that distinction.