Percentage Calculator
Five independent percentage tools on a single page: find a percentage of a number, work out what percent one value is of another, calculate increase or decrease, find the percentage difference, and add or subtract a percentage.
Last reviewed: 2026-07-29
Five independent percentage tools on a single page: find a percentage of a number, work out what percent one value is of another, calculate increase or decrease, find the percentage difference, and add or subtract a percentage.
Five independent tools. Fill in any card and press Calculate — other cards are not affected.
What is X% of Y?
X is what percent of Y?
Percentage increase or decrease
Percentage difference
Add or subtract a percentage
Calculations run locally in your browser. Your figures are not sent to a server or stored by us.
What is a percentage?
A percentage expresses a number as a fraction of 100. The word literally means “per hundred” — 20% means 20 out of every 100. Percentages are universal because they let us compare values on the same scale, regardless of the original units.
This page provides five independent tools, each visible at once. Fill in any card and press Calculate — the other cards are not affected. Use the discount calculator for sale price calculations, or the sales tax calculator for tax-inclusive pricing.
Percentage formulas
- X% of Y = (X ÷ 100) × Y
- X is what % of Y = (X ÷ Y) × 100
- % Change = (New − Old) ÷ |Old| × 100
- % Difference = |A − B| ÷ ((|A| + |B|) ÷ 2) × 100
- Add X%: Result = Original × (1 + X ÷ 100)
- Subtract X%: Result = Original × (1 − X ÷ 100)
Worked examples
Each card includes its own example. Here is a summary:
- What is 20% of 250? → 50
- 50 is what percent of 200? → 25%
- Percentage change from 80 to 100? → 25% increase
- Percentage difference between 80 and 100? → approximately 22.22%
- Add 15% to 200? → 230
How to use this calculator
Each card works independently. Type a value into the input field, press Calculate, and the result appears below with a Copy button. Pressing Enter in any field also calculates that card. Use Clear All to reset every card at once.
The sentence layout shows the question with inputs inline: “What is [20] % of [250]?” On mobile, the inputs stack vertically but the logic is the same.
Percentage change versus percentage difference
These two calculations look similar but answer different questions. Percentage change asks “how much did a value grow or shrink?” — it has a direction (increase or decrease) and requires an old and new value. Percentage difference asks “how far apart are these two values?” — it has no direction and divides by the average of the two.
Use percentage change when one value came before the other (e.g., last year vs this year). Use percentage difference when comparing two independent values (e.g., two test scores from different students).
Common percentage mistakes
- Adding percentages directly. A 20% increase followed by a 20% decrease does not return to the original. $100 → $120 → $96.
- Confusing change with difference. Change has a direction; difference does not.
- Dividing by the wrong base. “X is what percent of Y” divides X by Y, not Y by X.
- Calculating change from zero. Division by zero is undefined. Use absolute change instead.
- Forgetting the absolute value. Percentage change uses the absolute value of the old value in the denominator.
Frequently asked questions
Related calculators
- Discount Calculator
Calculate sale price, savings, stacked discounts and effective discount percentage.
- Sales Tax Calculator
Add or remove sales tax using any custom rate, with quantity support.
- VAT Calculator
Add or remove VAT using any custom rate, with net, gross and quantity support.
- Markup Calculator
Work out selling price and markup percentage from your unit cost.
Disclaimer
Results from this calculator are estimates for general information only and are not financial, accounting, tax, investment or legal advice. Verify important figures with a qualified professional. Read our full disclaimer.