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Percentage Calculator
Calculate basic %, percent change, reverse %, discount, tax, and marks in one place.
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Result
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The result, formula, and quick explanation will appear here.
Formula
- The formula steps for the selected calculation will appear here.
Examples
Load a ready-made example, then adjust the numbers to solve your own percentage problem.
What is a percentage?
A percentage shows how large one value is compared with another value out of 100. It is one of the easiest ways to compare parts, totals, gains, reductions, and academic scores.
Part of a whole
Use percentages for marks, attendance, survey responses, and sales shares.
Increase or decrease
Use percentages to compare old and new prices, traffic, salaries, or growth.
Discount or tax
Use percentages to estimate final price, savings, and tax-inclusive totals.
Reverse percentage
Work backwards when you know the final value after an increase or decrease.
Percentage formulas
These are the core formulas behind the calculator. They are written in plain language so you can check the answer yourself anytime.
1) What is X% of Y?
This is the formula used for discounts, tips, tax, and required marks.
Result = (Percentage ÷ 100) × Number
Example: 25% of 200 = (25 ÷ 100) × 200 = 50
2) X is what percent of Y?
This is the formula used for marks percentage, completion percentage, and share of total.
Percentage = (Part ÷ Whole) × 100
Example: 45 out of 60 = (45 ÷ 60) × 100 = 75%
3) Percentage increase or decrease
This formula compares a new value with an original value.
Percentage change = ((New − Old) ÷ Old) × 100
Example: From 80 to 100 = ((100 − 80) ÷ 80) × 100 = 25%
4) Reverse percentage
Reverse percentage helps when you know the final result and rate but need the original value.
Original after increase = Final ÷ (1 + Rate)
Original after decrease = Final ÷ (1 − Rate)
Step-by-step percentage methods
These short methods are useful when you want to solve percentage problems manually without opening a spreadsheet.
How to calculate X% of Y
- Write the percentage as a decimal by dividing it by 100.
- Multiply that decimal by the base value.
- Read the answer as the percentage value you wanted.
How to find what percent one number is of another
- Take the part value and divide it by the whole value.
- Multiply the result by 100.
- Add the percent sign to the final answer.
How to calculate percentage increase or decrease
- Subtract the original value from the new value.
- Divide that difference by the original value.
- Multiply by 100 to get the percentage change.
How to calculate reverse percentage
- Turn the percentage rate into a decimal.
- Create the multiplier: 1 + rate for an increase, 1 − rate for a decrease.
- Divide the final value by the multiplier to find the original value.
Common percentage table
This table helps with quick estimation, mental math, and everyday percentage questions.
| Percentage | Decimal | Fraction | Example |
|---|---|---|---|
| 10% | 0.10 | 1/10 | 10% of 250 = 25 |
| 12.5% | 0.125 | 1/8 | 12.5% of 80 = 10 |
| 15% | 0.15 | 3/20 | 15% of 200 = 30 |
| 20% | 0.20 | 1/5 | 20% of 75 = 15 |
| 25% | 0.25 | 1/4 | 25% of 320 = 80 |
| 33.33% | 0.3333 | 1/3 | 33.33% of 90 ≈ 30 |
| 50% | 0.50 | 1/2 | 50% of 64 = 32 |
| 75% | 0.75 | 3/4 | 75% of 48 = 36 |
| 100% | 1.00 | 1 | 100% of 42 = 42 |
Percentage change examples
Use this table to quickly understand how the percentage change formula behaves in common situations.
| Values | Difference | Result |
|---|---|---|
| From 80 to 100 | Difference = 20 | 25% increase |
| From 250 to 200 | Difference = -50 | 20% decrease |
| From 45 to 54 | Difference = 9 | 20% increase |
| From 120 to 90 | Difference = -30 | 25% decrease |
Where people use a percentage calculator
- Shopping: work out sale price, discount amount, stacked offers, or sales tax.
- Education: calculate test percentage, attendance percentage, grade percentage, or required marks.
- Business: measure growth, profit changes, conversion rate shifts, or target improvement.
- Finance: estimate rate-based changes, interest effects, or pricing differences.
- Daily life: calculate tips, commissions, budget changes, and percentage-based comparisons.
Marks percentage and grade guide
Grade systems vary, but this common guide is useful for quick reference when you convert marks to percentages.
| Percentage | Common grade | Meaning |
|---|---|---|
| 97% to 100% | A+ | Very strong score |
| 93% to 96% | A | Excellent performance |
| 90% to 92% | A− | Very good result |
| 83% to 89% | B | Strong overall score |
| 73% to 82% | C | Average to good range |
| 60% to 72% | D | Pass range in many systems |
| Below 60% | F | Below a common pass threshold |
Frequently asked questions
These questions cover the most common ways people search for a percentage calculator online.
How do I calculate what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, if 45 out of 60 questions are correct, the percentage is (45 ÷ 60) × 100 = 75%.
How do I find X% of Y?
Convert the percentage to a decimal and multiply it by the value. For example, 18% of 250 is 0.18 × 250 = 45.
What is the percentage change formula?
Percentage change = ((new value − original value) ÷ original value) × 100. A positive answer means increase. A negative answer means decrease.
How does reverse percentage work?
Reverse percentage works backwards from the final value. If a number increased by r%, divide the final value by (1 + r/100). If it decreased by r%, divide by (1 − r/100).
Can I use this page as a discount and tax percentage calculator?
Yes. The page includes discount, tax, and reverse-tax tools so you can find sale price, tax amount, total price, or price before tax.
How do I calculate marks percentage?
Marks percentage = (marks scored ÷ total marks) × 100. If you score 72 out of 80, the percentage is 90%.
What is the difference between percentage change and percent difference?
Percentage change uses one starting value as the base. Percent difference compares two values using their average as the base, so it treats both values equally.
Why do many percentage calculators show formulas and worked examples?
Showing the formula, steps, and examples helps people verify the result quickly, understand the method, and apply the same approach in exams, reports, shopping, and budgeting.
Related calculators
These tools answer nearby percentage questions and add useful internal paths for people exploring the topic further.
Why this page is designed this way
The page combines calculator modes, formulas, examples, tables, FAQs, references, and internal links because these elements help visitors answer both quick questions and deeper follow-up questions from one place.
- Multiple calculation modes cover basic %, reverse %, discount, tax, and marks queries on one URL.
- Visible formulas and worked examples make the page easier to trust and verify.
- Reference tables and FAQs help readers who search with long-tail questions instead of short keywords.
References
The formulas and explanations on this page were cross-checked with these public resources: