Four Percentage Calculators in One
This tool combines the four most common percentage calculations into a single page. All results update in real time as you type — no need to press a button.
What is X% of Y?
This is the most basic percentage calculation. It answers questions like "What is 15% of 200?" (answer: 30) or "What is 8.5% of 1,250?" (answer: 106.25). The formula is: result = (X ÷ 100) × Y.
Use this for: calculating discounts, tips, tax amounts, commissions, or any situation where you need to find a portion of a whole.
X is What Percent of Y?
This finds the percentage relationship between two numbers. For example, "45 is what percent of 180?" (answer: 25%). The formula is: result = (X ÷ Y) × 100.
Use this for: finding what fraction a part is of a whole, calculating completion percentages, or determining market share.
Percentage Change
This calculates how much something increased or decreased in percentage terms. For example, if a price went from 80 to 100, the percentage change is +25%. If it went from 100 to 80, it's −20%. The formula is: result = ((new − old) ÷ |old|) × 100.
Use this for: tracking price changes, measuring growth, comparing statistics across two time periods, or calculating inflation.
Increase / Decrease by a Percentage
This calculates what a number becomes after applying a percentage increase or decrease. For example, increasing 200 by 15% gives 230; decreasing 200 by 15% gives 170. Formulas: increase = value × (1 + %/100), decrease = value × (1 − %/100).
Use this for: applying discounts or markups, calculating salary raises, adjusting budgets, or projecting growth.
Frequently Asked Questions
What is the difference between percentage change and percentage points?
Percentage change is relative. If an interest rate goes from 2% to 3%, that's a 50% increase (it grew by half its original value). Percentage points are absolute — that same change is 1 percentage point. These are different things and are frequently confused in news reporting.
Why is decreasing by 50% and then increasing by 50% not back to the original?
Because percentages are calculated on different bases. Starting with 100, decreasing by 50% gives 50. Increasing 50 by 50% gives 75, not 100. The increase is calculated on the smaller value. This is why compound percentage changes are not simply additive.
How do I calculate a tip?
Use the "What is X% of Y?" calculator. Enter your tip percentage (e.g. 18) and the bill total. The result is the tip amount. Add it to the original total for the amount to pay. For splitting bills, check out the Tip Calculator tool.