What each mode calculates
"X% of Y" answers questions like "what is 15% of 200?" — useful for discounts, tips, and tax. "X is what % of Y" flips it around to answer "30 out of 200 is what percentage?" — handy for grading, survey results, or completion rates. "% increase / decrease" compares two numbers and tells you how much one has changed relative to the other, which is the calculation behind price changes, salary raises, and growth statistics.
Everyday uses for percentages
- Working out a discount at checkout or the final price after sales tax
- Calculating a tip at a restaurant
- Converting a test score or grade into a percentage
- Figuring out a pay raise or year-over-year growth rate
Frequently asked questions
How do I calculate a percentage increase?
Subtract the original value from the new value, divide by the original value, then multiply by 100. The "% increase / decrease" mode above does exactly this for you.
What's the difference between percentage points and percent?
If a rate moves from 20% to 25%, that's a 5 percentage-point increase, but a 25% relative increase (5 ÷ 20 × 100). The two describe the same change differently, and mixing them up is a common source of confusion in news and statistics.
Why is percentage change based on the "from" value?
Percentage change is always relative to the starting point, because that's the baseline you're measuring growth or decline against — the same absolute change looks like a bigger percentage when the starting value is small.