Calculate Percentages Online
A percentage calculator is an essential math tool used to quickly solve complex percentage problems. The word percentage comes from the Latin "per centum," meaning "by the hundred." Whether you need to figure out how to calculate percentage increase, find a percentage discount, or determine "what is X percent of Y," this tool does the math instantly.
How Our Percentage Calculator Works
This calculator solves the three most highly-searched percentage equations people encounter in finance, shopping, and math class:
1. What is X% of Y? (Percentage Discount)
Result = (X / 100) x Y
This formula converts the percentage into a decimal and multiplies it by the base number. It is perfect for calculating a tip at a restaurant or finding the exact dollar amount of a "20% off" sale. For example, 20% of 150 = (20 / 100) x 150 = 30.
2. X is what percent of Y?
Result = (X / Y) x 100
This divides the part by the whole to give you the percentage share. If a student answers 45 out of 180 questions correctly, what is their test score percentage? (45 / 180) x 100 = 25%.
3. Percentage Change (Increase / Decrease)
Result = ((New - Old) / |Old|) x 100
This is the standard percentage difference calculator formula. It measures how much a value has grown or shrunk relative to its original size. A positive result is a percentage increase; a negative result is a percentage decrease.
Common Real-World Examples
Finding Sales Tax & Retail Discounts
If a jacket is priced at $120 and advertised as 30% percent off, how much do you save? 30% of $120 is $36. Your final sale price is $84.
Calculating Revenue Growth
If a business had a revenue of $80,000 last year and $95,000 this year, what is the percentage increase? Using the formula: ((95,000 - 80,000) / 80,000) x 100 = an 18.75% revenue increase.
Avoid These Common Math Mistakes
- Base Value Errors in Percentage Change: Always divide by the original (old) value, not the new one. Dividing by the new value gives a completely different and incorrect result.
- Stacking Percentages: A 20% discount followed by an additional 10% off does not equal a 30% discount. The second discount applies to the newly reduced price, not the original price.