Percentage Calculator

How to use

1. Select Mode — Choose the type of percentage calculation you need
2. Enter Values — Input the numbers for your calculation
3. Get Result — Click Calculate to see the answer instantly

What Is a Percentage Calculator?

A percentage calculator is a tool that performs common percentage-based math operations. Percentages express a number as a fraction of 100 and are used everywhere — shopping discounts, tax rates, exam scores, financial returns, statistical data, and more.

This tool supports five calculation modes: finding a percentage of a number, determining what percentage one number is of another, calculating percentage change between two values, and computing values after a percentage increase or decrease.

Types of Percentage Calculations

What Is X% of Y?

This is the most common percentage calculation. Multiply the base number by the percentage divided by 100. Examples: 15% of 200 = 30. Sales tax of 8.5% on a $50 item = $4.25. A 20% tip on a $75 meal = $15.

X Is What Percent of Y?

Divide the part by the whole and multiply by 100. Examples: 45 out of 180 students passed → 25%. You saved $30 on a $120 item → 25% discount. You scored 85 out of 100 → 85%.

Percentage Change

Measures how much a value has increased or decreased relative to its original value. The formula is: ((New − Old) / |Old|) × 100. A positive result means increase, negative means decrease. Examples: Stock price from $50 to $65 → 30% increase. Weight from 180 to 165 lbs → 8.33% decrease.

Increase and Decrease

Calculate the new value after applying a percentage increase or decrease. Increase: Value × (1 + %/100). Decrease: Value × (1 − %/100). Examples: $80 increased by 25% = $100. $120 decreased by 15% = $102.

Real-World Applications

• Finance: Interest rates, investment returns, loan calculations, profit margins
• Shopping: Discount calculations, sales tax, tip amounts
• Education: Grade calculations, test scores, GPA computation
• Business: Revenue growth, market share, conversion rates, KPI tracking
• Health: BMI changes, calorie reductions, dosage adjustments

Common Percentage Mistakes

One frequent error is confusing percentage increase with percentage points. If a rate goes from 5% to 8%, it increased by 3 percentage points but by 60% relatively. Another common mistake is applying percentage changes sequentially — a 50% increase followed by a 50% decrease does not return to the original value (100 → 150 → 75).

Privacy

All calculations run locally in your browser. No data is sent to any server.

Calculate discounts with our Discount Calculator. Check your body mass index with our BMI Calculator. Calculate tips with our Tip Calculator.

Frequently asked questions

How do I calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. For example, 25% of 200 = (25 × 200) / 100 = 50.

How do I find what percentage one number is of another?

Divide the part by the whole and multiply by 100. For example, 30 is what % of 120? → (30 / 120) × 100 = 25%.

How is percentage change calculated?

Subtract the old value from the new value, divide by the absolute value of the old value, and multiply by 100. A result can be positive (increase) or negative (decrease).

What's the difference between percentage increase and percentage points?

A percentage increase is relative (10 to 15 is a 50% increase). Percentage points are absolute (from 10% to 15% is 5 percentage points).

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