Free Percentage Calculator
Instantly find what percent of a number is, calculate a discount, or measure percentage change between two values. Works for shopping, finance, school, and everyday math — no sign-up needed.
Percentage of Value
Find the final number when you know the percentage.
FORMULA: 20% of 100 = 20Percentage Change
Calculate the increase or decrease between two numbers.
FORMULA: ((Final - Initial) / Initial) × 100 = 50%How It Works
This calculator handles the three most common percentage problems people search for every day: finding what X% of a number is, calculating a percentage increase or decrease between two values, and measuring how much a number has changed relative to its original. Just enter your numbers — results appear instantly as you type.
Percentage Of
'What is 15% of 80?' — enter the percent and the total. Instantly see the value.
Percentage Change
'My salary went from $50K to $65K — what % increase is that?' Enter both numbers.
Percent Off
'This item is 30% off $120 — what do I pay?' Use the Percentage Of section.
What You Can Use It For
Percentages appear in almost every area of modern life. Here are the most common real-world situations where this calculator saves time:
The Math Behind It
Every result uses standard arithmetic — no approximations, no rounding until the final display step.
Accuracy & Limitations
Results are accurate to standard floating-point precision and displayed to 2 decimal places. This is sufficient for all everyday, commercial, and academic use cases. For very large numbers (>1 trillion) or scientific notation, a dedicated scientific calculator is preferable. Internal links: pair this tool with our Ratio Calculator for proportional problems, or the Average Calculator for statistical data sets. For finance-specific calculations see our Simple Interest Calculator.
Common Questions
20% of 80 is 16. Use the 'Percentage of Value' section: enter 20 as the percent and 80 as the total. The formula is (20 ÷ 100) × 80 = 16.
Subtract the old value from the new one, divide by the old value, then multiply by 100. Example: from 50 to 65 → ((65 − 50) ÷ 50) × 100 = 30% increase.
Use the Percentage of section. Enter the discount rate and the original price. The result is how much you save. Subtract it from the price to get the final amount you pay.
A percentage point is the arithmetic difference between two percentages (e.g., going from 10% to 15% is +5 percentage points). A percent change between those same figures is +50% relatively.
Yes. To add 18% GST to a price of $100: find 18% of 100 (= $18) and add it to the original. Total = $118. Our tool gives you the tax amount immediately.
Results use standard floating-point arithmetic and are accurate to the full precision of the input. The display rounds to 2 decimal places. For practical commercial or academic use this is more than sufficient.
When the final value is lower than the initial value, the percentage change is negative — indicating a decrease. For example: from 80 to 60 → −25%.