Tool overview
What the Percentage Calculator can do
This site brings together nine focused calculators covering the most common percentage problems people face every day. Every tool runs entirely in your browser, updates results as you type, and shows the formula behind each answer so you can check and learn at the same time.
Useful starting points
Choose the resource or calculator that best matches what you need to find.
Core Percentage Calculator
Find a percentage of a number, express a part as a percentage of a whole, or measure a percentage change between two values.
Open calculatorPercentage Increase Calculator
Measure how much a value has grown relative to where it started. Useful for salary changes, price rises, and sales growth.
Calculate an increasePercentage Decrease Calculator
Work out the percentage reduction from an original value. Helpful for sale prices, cost savings, and falling usage.
Calculate a decreaseDiscount Calculator
Enter a price and a discount percentage to see both the amount saved and the final sale price in one step.
Calculate a discountThe calculators available on this site
Each calculator is built around a single, well-defined question so you always know which one to reach for. The core calculator at the homepage handles three general questions: finding a percentage of a number, expressing a part as a percentage of a whole, and measuring percentage change between two values.
Five focused guide calculators cover percentage increase, percentage decrease, percentage difference, reverse percentage, and the 'what is X% of Y?' question. Three price-specific tools handle discounts, VAT (for UK and EU users), and sales tax (for US and international users).
Percentage of a number (X% of Y)
Multiply any number by a percentage to find the corresponding amount. Useful for tips, commissions, tax estimates, and portioning.
Formula: (percentage / 100) × value
Example: 15% of 200 = (15 / 100) × 200 = 30
Open X% of Y calculatorPercentage change (increase or decrease)
Measure how much a value has changed relative to its starting point. The sign tells you the direction: positive means growth, negative means a fall.
Formula: ((new − original) / |original|) × 100
Example: A rise from 80 to 100 = ((100 − 80) / 80) × 100 = 25%
Open percentage increase calculatorPercentage difference
Compare two independent values using their average as the reference. Unlike percentage change, switching the order of the values does not affect the result.
Formula: |value1 − value2| / ((value1 + value2) / 2) × 100
Example: Difference between 98 and 102 = |98 − 102| / 100 × 100 = 4%
Open percentage difference calculatorReverse percentage
Work backwards from a final value to find the original amount before a percentage change was applied. Particularly useful for removing tax or reversing a discount.
Formula: original = final / (1 ± percentage / 100)
Example: $90 after a 10% discount → $90 / 0.90 = $100 original
Open reverse percentage calculatorDiscount calculator
Enter an original price and discount rate to see the saving and the final price. Handles any percentage off, from small loyalty discounts to large clearance sales.
Formula: saving = price × (rate / 100); final = price − saving
Example: 20% off $75 → saving = $15; final price = $60
Open discount calculatorVAT calculator
Add VAT to a net amount or strip VAT from a gross total. Works with any VAT rate so it covers standard, reduced, and zero rates across different countries.
Formula: gross = net × (1 + rate / 100); net = gross / (1 + rate / 100)
Example: Add 20% VAT to £100 → £100 × 1.20 = £120 gross
Open VAT calculatorSales tax calculator
Calculate sales tax and the final checkout total. Enter the pre-tax price and your local tax rate to see the tax amount and all-in price.
Formula: tax = price × (rate / 100); total = price + tax
Example: 7.5% tax on $50 → tax = $3.75; total = $53.75
Open sales tax calculatorInstant calculation in the browser
Every calculator on this site runs entirely within your browser. There is no server call when you type a value — the result updates immediately as you change any input. This means calculations work whether you are online or offline, and no data you enter is sent anywhere.
The interactive fields use standard HTML number inputs, which means keyboard navigation, screen-reader announcements, and mobile numeric keyboards all work without any special configuration. Results are placed in ARIA live regions so screen readers announce changes automatically.
Mobile and accessibility support
The layout adapts to any screen size. On narrow screens, calculator cards stack vertically and input labels remain visible above their fields. On wider screens, related inputs sit side by side to reduce scrolling.
Color contrast ratios across the interface meet WCAG 2.1 AA guidelines. Focus states are visible for keyboard users. Each interactive element has a descriptive label so that assistive technology can identify it correctly.
How to choose the right calculator
Use the core calculator when your question is general: 'what is X% of a number?', 'what percentage is this part of the whole?', or 'how much has this value changed?'.
Reach for a focused calculator when your question has a specific context. Use the discount calculator when you want the saved amount and final price together. Use the VAT calculator when you need to add or remove tax from a price rather than express a percentage relationship. Use the reverse percentage calculator when you know the final value after a change but want to recover the original.
If you are not sure, the /guides page maps out each learning path and links to the most relevant tool for common scenarios.
Ready to calculate?
Open the core percentage calculator to get started, or jump directly to a focused tool for discounts, VAT, or tax.
Related percentage calculators
Use a focused calculator when your question needs a different baseline or a price-specific formula.
Percentage Calculator
Find a percentage, percentage ratio, or percentage change.
Percentage Increase Calculator
Measure how much a value has grown from its starting point.
Percentage Decrease Calculator
Work out the percentage reduction from an original value.
Percentage Difference Calculator
Compare two values when neither one is the original baseline.
Reverse Percentage Calculator
Find an original amount from a final value and percentage.
Discount Calculator
Calculate the amount saved and the final sale price.