Free Online Percentage Calculator – Calculate Percentages Instantly
Our Percentage Calculator is a free, fast, and easy-to-use online tool that handles the four most common percentage calculations in one place. Whether you need to find what percent of a number is, calculate a percentage increase or decrease, or work out the original value before a percentage was applied, this tool gives you an instant answer with the formula shown.
Used by students, shoppers, finance professionals, teachers, and business owners every day — percentage calculations are one of the most searched math topics on the internet worldwide.
The Four Percentage Calculators Explained
1. Percentage of a Number (X% of Y)
Find out what a given percentage of a number is. For example: What is 20% of 150? Enter 20 and 150 and the tool instantly returns 30. This is the most common percentage calculation, used for discounts, tips, tax, and scores.
2. What Percentage is X of Y?
Find out what percentage one number is of another. For example: 30 is what percent of 200? The answer is 15%. This is useful for calculating grades, completion rates, market share, and performance metrics.
3. Percentage Increase / Decrease
Calculate the percentage change between an original and a new value. For example: a price that went from 80 to 100 has increased by 25%. This mode is essential for tracking price changes, salary increases, weight loss progress, and business growth.
4. Reverse Percentage
Work backwards to find the original value before a percentage was added or removed. For example: if a price is now 120 after a 20% increase, what was the original price? The answer is 100. This is commonly used in VAT calculations, tax-inclusive pricing, and discount analysis.
How to Use the Percentage Calculator
- 1️⃣ Select the type of calculation you need from the options above
- 2️⃣ Enter the required numbers in the input fields
- 3️⃣ Click Calculate to see the result and the formula used
- 4️⃣ Use Reset to clear all fields and start a new calculation
Common Everyday Uses for Percentage Calculations
- 🛍️ Calculating sale discounts — how much you save on a 30% off item
- 🧾 Working out VAT or sales tax on a purchase
- 📊 Tracking business growth — revenue increase month over month
- 🎓 Converting test scores into percentages
- 💰 Calculating tips at a restaurant
- 📉 Measuring weight loss or fitness progress
- 🏦 Working out interest rates and loan percentages
- 📈 Analysing stock or crypto gains and losses
Percentage Formulas Reference
Here are the four formulas this calculator uses, so you can understand and verify each result:
- X% of Y: Result = (X ÷ 100) × Y
- What % is X of Y: Result = (X ÷ Y) × 100
- % Change: Result = ((New − Original) ÷ |Original|) × 100
- Reverse %: Original = Final ÷ (1 + Rate ÷ 100)
Who Should Use This Percentage Calculator?
- 🎓 Students solving maths homework and exam questions
- 🛒 Shoppers calculating discounts and comparing sale prices
- 💼 Business professionals tracking KPIs, growth, and margins
- 🧑🏫 Teachers preparing examples and grading assignments
- 🏦 Finance and accounting professionals working with tax and interest
- 📱 Anyone who needs a quick and reliable percentage answer on the go
Why Use Our Free Percentage Calculator?
- ✅ 100% free with no sign-up required
- ✅ Four calculation modes in one single tool
- ✅ Shows the formula alongside every result — great for learning
- ✅ Works on all devices — mobile, tablet, and desktop
- ✅ Instant results with no page reload
- ✅ No data is stored or transmitted
Frequently Asked Questions
How do I calculate 20% of a number?
Select % of a number, enter 20 in the percentage field and your number in the second field, then click Calculate. The formula used is: (20 ÷ 100) × your number.
How do I calculate a percentage increase?
Select % increase / decrease, enter the original value and the new value, then click Calculate. The tool will tell you whether it is an increase or decrease and by how much.
What is a reverse percentage?
A reverse percentage lets you find the original value before a percentage was added or removed. For example, if a product costs £120 after a 20% markup, the reverse percentage calculation tells you the original price was £100.
How accurate are the results?
Results are calculated with up to four decimal places of precision, covering the needs of most everyday, academic, and professional use cases.
Is this percentage calculator free?
Yes, completely free. No account, no subscription, and no usage limits. All four calculation modes are available at no cost.