Percentage Calculator
Five percentage tools in one — no formula memorization needed.
A percentage expresses a number as a fraction of 100. This calculator handles the five most common percentage questions: What is X% of Y?, X is what percent of Y?, percentage change from X to Y, a value increased or decreased by a percent, and percentage point difference. All five compute instantly — enter two numbers and see your answer in real time.
How Each Percentage Formula Works
Every percentage calculation reduces to one of five core operations. Knowing which formula applies is the only real challenge — which is why this tool auto-selects the right one.
① What is X% of Y?
Result = Y × (X ÷ 100)
Example: 15% of 200 = 200 × 0.15 = 30
② X is what % of Y?
Result = (X ÷ Y) × 100
Example: 30 is what % of 200? = (30 ÷ 200) × 100 = 15%
③ Percentage Change from X to Y
Result = ((Y − X) ÷ |X|) × 100
Example: from 80 to 100 = ((100 − 80) ÷ 80) × 100 = +25%
④ Increase/Decrease X by Y%
Increase: X × (1 + Y/100) | Decrease: X × (1 − Y/100)
Example: 200 increased by 25% = 200 × 1.25 = 250
⑤ Percentage Points (pp) Difference
Result = Y% − X% (simple subtraction)
Example: from 45% to 60% = 60 − 45 = +15 pp (not 33.3%)
| Question | Formula | Common Use |
|---|---|---|
| X% of Y | Y × X/100 | Tips, discounts, tax |
| X is _% of Y | (X÷Y)×100 | Grades, market share |
| % change | ((Y−X)/|X|)×100 | Revenue growth, price changes |
| Increase/decrease | X×(1±Y/100) | Raises, markups, discounts |
| pp difference | Y − X | Interest rates, poll changes |
💡 Pro-Tip
Percent vs. Percentage Points — The Most Misunderstood Distinction in Finance: When the Fed raises rates from 2% to 2.5%, news anchors say "rates rose 50 basis points" or "0.5 percentage points." They do NOT say rates rose 25% — even though (2.5 − 2) ÷ 2 × 100 = 25%. Percentage points measure the raw arithmetic gap; percent measures the relative change. Getting this wrong in negotiations, analysis, or presentations signals a fundamental misunderstanding. Always specify: are you comparing percentage points or relative percent change?
Percentage Calculator
What is X% of Y?
30
15% of 200
X is what % of Y?
15%
30 ÷ 200 × 100
Percentage Change (from X to Y)
+25%
increase
Increase / Decrease X by Y%
250
200 × 1.2500
Percentage Points Difference (Y − X)
+15 pp
percentage points
Based on your results — what to do next:
How much has inflation eroded your money?
If prices rose 100 from 80, that's a 25% change in purchasing power.
What % of income should you save?
Knowing percentages is key — the 50/30/20 rule means 20% of income to savings.
How fast does a % return compound?
A 15% annual return on 200 grows dramatically over time thanks to compounding.
Percentage Calculator FAQ
What is 20% of 150?
20% of 150 = 150 × 0.20 = 30. Multiply the number by the percentage divided by 100. Quick mental math shortcut: 20% = 2× the 10% value. 10% of 150 = 15, so 20% = 30.
How do I find the percentage of two numbers?
Divide the part by the whole and multiply by 100. Example: you scored 45 out of 60 on a test. 45 ÷ 60 × 100 = 75%. This is the "X is what % of Y" formula. The part (45) goes in the numerator; the whole (60) goes in the denominator.
How do I calculate a percentage discount?
Use "decrease X by Y%": New Price = Original × (1 − Discount%). Example: $80 shirt with 30% off = $80 × 0.70 = $56. The savings = $80 × 0.30 = $24. Alternatively, use the "X% of Y" mode to find the discount amount, then subtract from the original price.
What is the difference between percent and percentage points?
Percentage points (pp) are absolute: if approval goes from 40% to 45%, it rose 5 pp. Percent is relative: 5 ÷ 40 × 100 = 12.5% increase. Both are correct — they measure different things. Politicians prefer "pp" when the change is small; critics prefer "%" to make it sound dramatic.
How do I reverse a percentage calculation?
To find the original number before a percent change: divide the result by (1 + rate) for increases, or (1 − rate) for decreases. Example: a price after a 20% increase is $120. Original = $120 ÷ 1.20 = $100. Useful for backing out sales tax or figuring out the pre-raise salary.
How do I calculate a percentage raise?
Use "increase X by Y%". If your salary is $65,000 and you get a 5% raise: $65,000 × 1.05 = $68,250. The raise amount = $65,000 × 0.05 = $3,250. To calculate what percentage raise you received: ((new − old) ÷ old) × 100 — the "percentage change" formula.