How to Use Percentage Calculator: Complete Guide (2026)

What is Percentage Calculator?

A percentage calculator solves everyday percent problems: what is X% of a number, what is the percent change between two values, and what percent one number is of another. ToolsMinify's free Percentage Calculator covers all three modes with instant results - useful for tips, discounts, taxes, grades, and quick business math - entirely in your browser.

Free online percentage calculator: find the percentage of a number, calculate percent change (increase or decrease), and work out what percent X is of Y - with the formula and instant results.

Why use Percentage Calculator?

• Find a percentage of a number (tips, taxes, discounts)
• Calculate percent increase or decrease between two values
• Answer "X is what % of Y" without rearranging formulas
• Instant results as you type - no submit button
• Private and free - numbers never leave your device

How to use Percentage Calculator - step by step

1. Step 1: Choose the calculation mode: '% of a number', '% change', or 'X is what % of Y'.
2. Step 2: Enter your values in the two fields.
3. Step 3: Read the computed result instantly - no button to press.
4. Step 4: Switch modes to solve a different type of percentage problem.

The Percentage Calculator lives under Calculator Tools. Open the tool page, enter your input in the main field, and results update instantly. Use the copy button to paste output into documents, code editors, or spreadsheets.

Common use cases

Tips, tax, and discounts

Use "% of a number" for a 20% tip, sales tax, or a percent-off amount before checkout.

Growth and performance

Use "% change" to see how much revenue, traffic, or grades went up or down between two periods.

Shares and ratios

Use "X is what % of Y" for exam scores, completion rates, or part-of-whole breakdowns.

Quick business checks

Estimate margins, commission, or goal progress without opening a spreadsheet.

Examples

• Percentage of a number: 15% of 200 = 30.
• Percentage increase: From 80 to 100 is a 25% increase.
• What percent is X of Y: 30 is 15% of 200.
• Tip calculation: 20% of a $45 bill is a $9 tip.

Pro tips

• Percent change = ((new - old) / old) × 100 - a drop from 100 to 80 is a 20% decrease, not 20 points of a different base.
• For sale prices, Discount Calculator shows final price and savings when you already think in "% off".
• Enter the whole number as the base for "X is what % of Y" - swapping them inverts the answer.
• Decimals are fine (e.g. 12.5%); the tool does not require whole percentages.
• Pair with CPM Calculator when ad math needs both percent-of-budget and cost-per-mille figures.

Frequently asked questions

How do I calculate a percentage?

To find a percentage of a number, multiply the number by the percentage divided by 100. Formula: result = (percentage / 100) x number. For example, 25% of 80 = (25 / 100) x 80 = 20. Use the '% of a number' mode above to do it instantly.

How do I use the percentage calculator?

Pick the mode that matches your question, type the two numbers, and read the answer. Use '% of a number' for things like tips and taxes, '% change' to compare an old and new value, and 'X is what % of Y' to turn a fraction into a percentage.

What is the difference between percent of a number and percent change?

"Percent of a number" finds a portion - e.g. 15% of 200 = 30. "Percent change" calculates how much something increased or decreased between two values - e.g. from 80 to 100 is a 25% increase. "X is % of Y" finds what percentage one number is of another - e.g. 30 is 15% of 200.

How do I calculate a percentage increase?

Use the "% change" tab. Enter the original value as the starting number and the new value. The tool calculates: ((New - Old) ÷ Old) × 100. A positive result means increase; negative means decrease.

How do I work out a tip percentage?

Use the "% of number" tab. Enter the bill amount and the tip percentage (e.g. 15 or 20). The result is the tip amount. Add it to the original bill for the total.

What is the formula for percentage of a number?

Result = (Percentage ÷ 100) × Number. For example, 25% of 80 = (25 ÷ 100) × 80 = 20.

Is this calculator accurate for VAT and sales tax?

Yes for simple tax calculations. Enter 100 (original price) and your VAT rate (e.g. 20) in the "% of number" tab to find the tax amount (20). Add to the original for the total (120). For reverse VAT (finding pre-tax price), use the "X is % of Y" tab.

Related tools you might need

Explore other calculator tools on ToolsMinify. Related utilities are linked on the Percentage Calculator page to help you complete your workflow without leaving the site.