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Percentage Calculator

Pick your question type, enter two numbers, get the answer instantly — with a full explanation

🔢
What is X% of Y?
e.g. What is 20% of 80?
❓
X is what % of Y?
e.g. 15 is what % of 60?
📈
% Increase / Decrease
e.g. 50 to 75 = how much %?
What is  ___  %  of  ___  ?
Enter the percentage number (without the % sign)
Enter the number you want to find the percentage of
Answer
—
10% of 200
= 20
25% of 80
= 20
15% of 60
= 9
___  is what % of  ___  ?
The smaller number (the "part")
The bigger number (the "whole")
Answer
—%
30 of 120
= 25%
45 of 180
= 25%
7 of 28
= 25%
From  ___  to  ___  — what is the % change?
The starting / original number
The ending / new number
Answer
—%
50 → 75
+50% increase
100 → 80
−20% decrease
200 → 250
+25% increase
📚 Percentage Formula Cheat Sheet
What is X% of Y?
Answer = (X ÷ 100) × Y
20% of 80 = (20÷100)×80 = 16
X is what % of Y?
Answer = (X ÷ Y) × 100
15 of 60 = (15÷60)×100 = 25%
% Increase
((New − Old) ÷ Old) × 100
50→75: ((75−50)÷50)×100 = +50%
% Decrease
((Old − New) ÷ Old) × 100
100→80: ((100−80)÷100)×100 = 20%

Common Percentage Questions

How do I calculate percentage in my head?+
Use these shortcuts: 10% = divide by 10. 5% = half of 10%. 20% = divide by 5. 25% = divide by 4. 50% = divide by 2. Example: 15% of 80 → 10% is 8, 5% is 4, so 15% = 8+4 = 12.
What is the difference between percentage and percentile?+
Percentage is a ratio out of 100 (e.g., you scored 80%). Percentile is a rank — it tells you what % of people scored below you (e.g., 90th percentile = you scored better than 90% of people). In exams, you want a high percentile.
How do I find what percent one number is of another?+
Divide the part by the whole, then multiply by 100. Example: what percent is 18 of 72? → (18 ÷ 72) × 100 = 25%. Use the middle tab "X is what % of Y" on this calculator.
How do I calculate percentage marks in an exam?+
Divide your marks by total marks, then multiply by 100. Example: you scored 432 out of 500 → (432 ÷ 500) × 100 = 86.4%. Use the "X is what % of Y" tab above — enter your marks as the part and total marks as the whole.
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Percentage Calculator — How Percentages Work in Real Life

Percentages are one of the most practically useful math concepts — yet also one of the most frequently misunderstood. The word "percent" literally means "per hundred." So 35% means 35 out of every 100, or the fraction 35/100 = 0.35. Whether you're calculating a tip, figuring out a discount, understanding your raise, or analyzing data, the same core formulas apply everywhere.

The Three Core Percentage Formulas

Every percentage problem boils down to one of three questions: (1) What is X% of Y? — multiply Y by (X/100). Example: 15% of $80 = 80 × 0.15 = $12. (2) X is what percent of Y? — divide X by Y and multiply by 100. Example: $12 is what % of $80? = (12/80) × 100 = 15%. (3) X is Y% of what? — divide X by (Y/100). Example: $12 is 15% of what? = 12 ÷ 0.15 = $80.

Percentage Change vs Percentage Points — A Critical Distinction

This is one of the most commonly confused concepts in statistics and journalism. If an interest rate rises from 2% to 3%, it increased by 1 percentage point — but by 50% in percentage terms (1/2 × 100). A politician might say "crime fell by 2 percentage points" (from 10% to 8%) or "crime fell by 20%" — both are technically correct but create very different impressions. Always check which type of percentage change is being reported.

Common Percentage Mistakes to Avoid

Percentage increases and decreases are not symmetrical. If a stock falls 50%, it needs to rise 100% to get back to where it started — not 50%. If your salary increases 20% and then decreases 20%, you don't end up where you started: $50,000 → $60,000 → $48,000. This asymmetry is why percentage changes need careful interpretation, especially with investments and prices over time.