Percentage Calculator – 8 Free Tools | What is X% of Y, Percentage Change, Increase & More

8 Free Percentage Tools in One Page

Percentage Calculator

Every percentage formula you'll ever need — percentage of a number, change, increase, decrease, difference, and reverse percentage — with instant step-by-step explanations.

Tool 1 of 8

What is X% of Y?

Find any percentage of any number instantly

Formula: Result = (Percentage ÷ 100) × Number

Percentage (%)

Number

Try: 10% of 200 25% of 1200 15% of 85 7.5% of 400

Enter a percentage and a number to see the result.

—

Step-by-Step

Tool 2 of 8

Percentage Change Calculator

Calculate the % change from one value to another (increase or decrease)

Formula: Change% = ((New − Old) ÷ Old) × 100

Original (Old) Value

→

New Value

Try: 100→150 200→180 50→75

↗

Enter original and new values to calculate percentage change.

—

Step-by-Step

Tool 3 of 8

Percentage Increase Calculator

Find the new value after a percentage increase

Formula: New Value = Original × (1 + Increase% ÷ 100)

Original Value

Increase by (%)

Try: $1000 +10% 250 +20% 85 +5%

▲

Enter the original value and increase percentage.

—

Step-by-Step

Tool 4 of 8

Percentage Decrease Calculator

Find the new value after a percentage decrease or discount

Formula: New Value = Original × (1 − Decrease% ÷ 100)

Original Value

Decrease by (%)

Try: $120 −25% 350 −10% $99 −15%

▼

Enter the original value and decrease percentage.

—

Step-by-Step

Tool 5 of 8

X is What Percent of Y?

Find what percentage one number is of another

Formula: Percentage = (X ÷ Y) × 100

Number (X)

is what % of

Total (Y)

Try: 30 of 120 75 of 300 17 of 68

Enter both numbers to find the percentage relationship.

—

Step-by-Step

Tool 6 of 8

Percentage Difference Calculator

Find the percentage difference between two values (order-independent)

Formula: Diff% = |V1 − V2| ÷ ((V1 + V2) ÷ 2) × 100

Value 1

↔

Value 2

Try: 90 vs 110 500 vs 350

↔

Enter two values to find the percentage difference between them.

—

Step-by-Step

Tool 7 of 8

Reverse Percentage Calculator

Find the original value before a percentage was applied — great for finding pre-tax or pre-discount prices

Formula: Original = Final Value ÷ (1 ± Percentage ÷ 100)

Final Value (after percentage)

Percentage Applied (%)

Was it an increase or decrease?

Try: $85 after −15% 120 after +20%

↩

Enter the final value and the percentage that was applied.

—

Step-by-Step

Tool 8 of 8

Percentage of Total Calculator

Break down what share (%) each part contributes to the whole

Formula: Part% = (Part ÷ Total) × 100

Part Value

out of

Total Value

Try: 35 of 140 7 of 28 480 of 1200

Enter the part and total to see what percentage the part represents.

—

Step-by-Step

Complete Guide

How to Calculate Percentages: Every Formula Explained

Percentages appear in almost every area of daily life — from calculating discounts and tax to understanding pay rises, exam scores, and investment returns. This guide covers all 8 types of percentage calculations with real-world examples and easy-to-follow formulas.

Finding X% of a Number

The most common percentage question. To find 20% of 500: divide 20 by 100 to get 0.2, then multiply by 500 to get 100. Used for: tips, discounts, commission, tax, and exam marks.

↗

Percentage Change

Measures how much a value grew or shrank relative to its starting point. If a stock moved from $80 to $100: (100−80) ÷ 80 × 100 = +25%. Negative results mean a decrease. Used in finance, sales, and analytics.

↩

Reverse Percentage

Work backwards to find the original value. If a product costs $85 after a 15% discount, the original price was 85 ÷ 0.85 = $100. Useful for VAT-exclusive prices, pre-discount values, and tip calculations.

↔

Percentage Difference

Unlike percentage change, this is order-independent — comparing 90 and 110 gives the same result as comparing 110 and 90. Formula uses the average as the denominator: |90−110| ÷ 100 × 100 = 20%.

📐 Real-World Percentage Examples

What is 18% tip on a $65 restaurant bill?$11.70

Sales rose from 4,000 to 5,200 units — what's the % increase?+30%

A laptop costs $850 after a 15% discount — original price?$1,000

You scored 68/85 on an exam — what percentage is that?80%

Price dropped from £240 to £180 — what's the percentage decrease?−25%

Formula Reference

All 8 Percentage Formulas at a Glance

Calculation Type	Formula	Example
X% of Y	(X ÷ 100) × Y	20% of 500 = 100
% Change	((New − Old) ÷ Old) × 100	80 to 100 = +25%
% Increase	Original × (1 + P ÷ 100)	500 + 20% = 600
% Decrease	Original × (1 − P ÷ 100)	200 − 25% = 150
X is what % of Y	(X ÷ Y) × 100	45 ÷ 180 × 100 = 25%
% Difference	\|V1−V2\| ÷ avg(V1,V2) × 100	90 vs 110 = 20%
Reverse % (decrease)	Final ÷ (1 − P ÷ 100)	85 after −15% = 100
% of Total	(Part ÷ Total) × 100	250 ÷ 1000 × 100 = 25%

FAQ

Frequently Asked Percentage Questions

What is the difference between percentage change and percentage difference? +

Percentage change measures how a value shifts from a specific starting point — it's directional (positive = increase, negative = decrease) and the order matters. Percentage difference, on the other hand, is order-independent and compares two values symmetrically using their average as the denominator. Use percentage change for before/after comparisons; use percentage difference when comparing two independent values with no clear "base."

How do I calculate percentage increase from one number to another? +

Subtract the original value from the new value, divide by the original value, then multiply by 100. Example: from 120 to 150 → (150 − 120) ÷ 120 × 100 = 25% increase. If the result is negative, it's a decrease. Our % Change calculator (Tool 2) handles both directions automatically.

How do I find the original price before a discount? +

Use the reverse percentage formula: divide the discounted price by (1 − discount% ÷ 100). So if an item costs $68 after a 15% discount: $68 ÷ 0.85 = $80 original price. This works for VAT-included prices, sale prices, and any scenario where a percentage has already been applied.

How do you calculate what percentage one number is of another? +

Divide the first number by the second and multiply by 100. Example: "what percentage is 35 of 140?" → 35 ÷ 140 × 100 = 25%. This is useful for exam scores, market share calculations, survey results, and budget breakdowns.

Why do percentage increases and decreases not cancel each other out? +

Because they apply to different base values. Increase 100 by 50% = 150. Then decrease 150 by 50% = 75 — not back to 100. The decrease applies to the new, larger number. To reverse a 50% increase, you'd need to decrease by 33.3% (1 ÷ 1.5 − 1). This is a common source of confusion in finance and retail.

Percentage Calculator

Step-by-Step

Step-by-Step

Step-by-Step

Step-by-Step

Step-by-Step

Step-by-Step

Step-by-Step

Step-by-Step

How to Calculate Percentages: Every Formula Explained

Finding X% of a Number

Percentage Change

Reverse Percentage

Percentage Difference

📐 Real-World Percentage Examples

All 8 Percentage Formulas at a Glance

Frequently Asked Percentage Questions

Get New Tools First