Percentage Calculator
Instantly solve any percentage problem — find a percentage of a number, calculate what percent one value is of another, or reverse-calculate the whole from a part and its percentage.
Last updated: March 2026
How to Use the Percentage Calculator
- Select your calculation type from the dropdown — choose the scenario that matches your question.
- Enter the two known values in the input fields. Labels update to reflect your selected mode.
- See your answer instantly — the result, formula, and step-by-step working appear automatically.
- Use Clear to reset all fields and start a new calculation, or Share to copy the link with your values pre-filled.
What Is a Percentage?
A percentage is a number or ratio expressed as a fraction of 100. The word comes from the Latin per centum, meaning "by the hundred." When you say 45%, you mean 45 out of every 100 — or equivalently, the decimal 0.45, or the fraction 45/100 (simplified to 9/20).
Percentages appear everywhere in daily life: a bank charges 6.5% interest per year; a store offers 30% off; a student scores 87% on an exam; a city's population grew by 2.3% last year. Knowing how to move fluidly between percentages, decimals, and fractions is one of the most practical math skills you can have.
The Three Core Percentage Problems
Every percentage problem reduces to one of three question types:
- Finding the part: "What is 25% of 80?" → Part = (Percentage / 100) × Whole = 0.25 × 80 = 20
- Finding the percentage: "20 is what percent of 80?" → Percentage = (Part / Whole) × 100 = (20/80) × 100 = 25%
- Finding the whole: "20 is 25% of what number?" → Whole = Part / (Percentage / 100) = 20 / 0.25 = 80
This calculator handles all three types automatically. Just select your mode and enter the two known values.
Real-World Percentage Applications
Shopping Discounts
Retail discounts are one of the most common uses of percentages. A 40% off sale on a $150 jacket means you save $60 (150 × 0.40) and pay $90. To quickly estimate discounts in your head: a 10% discount is always the first digit moved one place right — 10% of $340 is $34. Double it for 20%, halve it for 5%.
Sales Tax and VAT
Adding tax means increasing a price by a percentage. A $200 item with 8.5% sales tax costs $200 × 1.085 = $217. Notice you multiply by 1 + rate (not just the rate) to get the final price in one step. Reverse calculation — finding the pre-tax price from a total — uses the formula: Pre-tax = Total ÷ (1 + tax rate). So a $217 total with 8.5% tax has a pre-tax price of $217 ÷ 1.085 = $200.
Tips and Gratuities
A common shortcut for a 20% tip: move the decimal one place left (10%), then double it. On a $43 bill: 10% = $4.30, doubled = $8.60. For 15%: take 10% ($4.30) and add half of that ($2.15) = $6.45. For 18%, find 10% + 5% + 3%.
Interest Rates and Finance
Annual percentage rates (APR) for loans, credit cards, and savings accounts are all expressed as percentages. A credit card with 24% APR charges roughly 2% per month on your balance. Understanding how to calculate compound interest percentages helps you compare financial products and plan investments effectively.
Statistics and Data
Percentages are the universal language of statistics. When 1,500 out of 6,000 survey respondents agree with a statement, that's 25%. Expressing counts as percentages lets you compare groups of very different sizes — an essential skill for reading news, research, and business reports.
Percentage Shortcuts and Mental Math Tricks
Competitive calculators rarely teach mental math — here's your advantage:
The 10% Anchor Method
Any percentage of a number can be built from 10%. Calculate 10% first (shift decimal left), then scale. 35% = 10% + 10% + 10% + 5% (half of 10%). Example: 35% of 240: 10% = 24, × 3 = 72, + 5% (12) = 84.
Reversibility Rule
X% of Y always equals Y% of X. So 4% of 75 = 75% of 4 = 3. This trick often makes calculations much easier — 8% of 25 = 25% of 8 = 2.
Percent vs. Percentage Point
These are different. If a loan rate rises from 4% to 6%, it rose by 2 percentage points — but by 50% relative to the original rate ((6-4)/4 × 100 = 50%). This distinction matters enormously in finance and journalism.
Fraction Equivalents to Memorize
- 10% = 1/10 | 20% = 1/5 | 25% = 1/4 | 33.33% ≈ 1/3
- 50% = 1/2 | 66.67% ≈ 2/3 | 75% = 3/4 | 100% = 1
- 12.5% = 1/8 | 37.5% = 3/8 | 62.5% = 5/8 | 87.5% = 7/8
Common Percentage Examples
What is 10% of 1000?
10% of 1,000 is 100. Move the decimal point one place to the left: 1000 → 100. This works for any number — 10% of 847 = 84.7.
What is 15% of 200?
15% of 200 is 30. Calculate: 200 × 0.15 = 30. Alternatively: 10% of 200 = 20, plus 5% of 200 = 10, total = 30.
What is 25% of 80?
25% of 80 is 20. Since 25% = 1/4, simply divide by 4: 80 ÷ 4 = 20.
What is 30 as a percentage of 120?
30 is 25% of 120. Formula: (30 ÷ 120) × 100 = 25%.
What is 50 as a percentage of 200?
50 is 25% of 200. Formula: (50 ÷ 200) × 100 = 25%.
75 is 60% of what number?
75 is 60% of 125. Formula: 75 ÷ 0.60 = 125. Check: 125 × 0.60 = 75. ✓
What is 5% of 1,200?
5% of 1,200 is 60. Find 10% first: 120, then halve it: 60.
What is 18% of 50?
18% of 50 is 9. Use reversibility: 18% of 50 = 50% of 18 = 9.
What percent is 45 of 180?
45 is 25% of 180. (45 ÷ 180) × 100 = 25%.
What is 8.5% of 2,000?
8.5% of 2,000 is 170. Calculate: 2,000 × 0.085 = 170. This is a common sales tax scenario.
People Also Search For
How to calculate percentage of marks
Percentage of marks = (Marks Obtained ÷ Total Marks) × 100. If you scored 450 out of 600: (450 ÷ 600) × 100 = 75%. This applies to individual subjects or combined totals across multiple tests.
How to calculate percentage increase or decrease
Percentage change = ((New − Old) ÷ |Old|) × 100. A positive result is an increase; negative is a decrease. Example: price goes from $40 to $50: ((50 − 40) ÷ 40) × 100 = 25% increase. Use our Percentage Change Calculator for this specific calculation.
How to find a percentage of a total
Part = (Percentage ÷ 100) × Total. To find 35% of 400: (35 ÷ 100) × 400 = 140. This is the most common percentage problem type — enter your values in "What is X% of Y?" mode above.
Percentage vs. percentile — what's the difference?
A percentage measures a ratio out of 100; a percentile shows your rank within a group. Scoring 80% on a test means you got 80 out of 100 questions right. Being in the 80th percentile means you scored higher than 80% of test-takers — your actual score could be anything.
How to calculate percentage with a calculator
On most calculators: enter the number, press ×, enter the percentage, press the % key. On a phone calculator: 500 × 20% = 100. Or use this free online tool — enter two values and get the answer with full formula explanation instantly.
How to reverse calculate a percentage
To find the original value before a percentage was applied: divide by (1 + rate) for increases, or (1 − rate) for decreases. If a price after a 20% markup is $120: original = $120 ÷ 1.20 = $100. Use the "X is Y% of what?" mode in this calculator for direct reverse percentage calculations.
Percentage Calculator — Frequently Asked Questions
What is the percentage formula?
The core formula is: Percentage = (Part ÷ Whole) × 100. Rearranged: Part = (Percentage ÷ 100) × Whole, and Whole = Part ÷ (Percentage ÷ 100). This calculator applies the correct rearrangement based on your selected mode.
What is 20% of 500?
20% of 500 is 100. Calculation: 500 × (20/100) = 500 × 0.20 = 100.
How do I calculate a percentage increase?
Percentage increase = ((New Value − Old Value) ÷ Old Value) × 100. If a salary goes from $50,000 to $55,000: ((55,000 − 50,000) ÷ 50,000) × 100 = 10% increase.
How do I find what percent one number is of another?
Divide the first number by the second, then multiply by 100. "30 is what percent of 150?" → (30 ÷ 150) × 100 = 20%. Select "X is what % of Y?" mode in the calculator above.
What is the difference between percentage and decimal?
A percentage divides the whole into 100 equal parts and uses the % symbol. A decimal expresses the same ratio in standard notation. To convert: divide % by 100 to get the decimal (25% = 0.25), or multiply the decimal by 100 to get the % (0.25 = 25%).
How do I add a tax percentage to a price?
Multiply the price by (1 + tax rate as decimal). For 10% tax on $80: $80 × 1.10 = $88. This is faster than calculating the tax separately and adding it.
How do I calculate a tip?
Tip = Bill Amount × (Tip % ÷ 100). For a 20% tip on $65: $65 × 0.20 = $13. A quick mental shortcut: 20% tip = double the 10% value. 10% of $65 = $6.50, doubled = $13.
What does percent off mean?
"Percent off" means you subtract that percentage from the original price. 25% off $200 means you pay 75% of $200: $200 × 0.75 = $150. You save $50.
Can percentages exceed 100%?
Yes. A percentage over 100% simply means the part is larger than the whole. If you earned $120 from investing $100, your return is 120% of the original — or a 20% profit. Percentages can also be negative (indicating loss or decrease).
Is this calculator accurate for financial calculations?
This calculator uses standard floating-point arithmetic and rounds results to 6 decimal places, which is sufficient for most everyday percentage calculations. For critical financial or accounting work, verify important results and consult a qualified accountant for tax or investment decisions.
Does this calculator store my data?
No. All calculations are performed entirely in your browser using JavaScript. No numbers are transmitted to any server, and nothing is stored or logged. Your data never leaves your device.