Percentage Calculator
Calculate percentages easily with 5 different calculation modes
Five Percentage Calculators in One — Instant, Accurate Results
Whether you need to find a percentage of a number, calculate marks percentage, work out a discount, or find the original price before a percentage change — this tool handles all five common percentage calculations instantly.
5 Calculation Modes
Switch between five distinct percentage calculations: find X% of Y, determine what percentage X is of Y, calculate percentage increase or decrease, convert marks to percentage, and find the original value before a known percentage change. Every common percentage problem is covered in one place.
Formula Shown With Every Result
Every calculation displays the formula used alongside the answer, so you understand the math behind the result. This makes the calculator a learning tool as well as a computing tool — you can verify the logic and use the formula independently in exams or work.
Marks to Percentage Conversion
A dedicated mode for students to instantly convert total marks obtained out of total marks to a percentage. Enter 385 out of 500, or 72 out of 80 — the calculator gives your exact percentage immediately. Works for board exams, entrance tests, university exams, and any scored assessment.
Percentage Increase and Decrease
Calculate how much something has increased or decreased as a percentage. Enter the original and new value to find the exact percentage change — whether it is a salary hike, a price drop, a population change, or a test score improvement. Correctly identifies both increases and decreases with the right sign.
Find the Original Value
Work backwards from a final value and a known percentage change to find the original. For example, if a product now costs ₹850 after a 15% discount, what was the original price? Enter the final value and percentage change, and the calculator instantly returns the original pre-change value.
Free, Fast, and No Sign-Up
Completely free with no account or registration required. Results appear instantly — no submit button needed on most modes. Works on any device including mobile. Use the Copy Result button to save your answer. No data is stored, ensuring complete privacy with every calculation.
All Five Percentage Calculation Modes Explained
Each mode solves a different percentage problem. Here is what each one does, the formula it uses, and when to use it.
Mode 1 — What is X% of Y?
Use this to find a specific percentage of any number. Examples: What is 15% of 2,400? What is 8.5% GST on ₹1,200? What is 30% off ₹3,500? Enter the percentage and the base number to get the answer instantly. The most commonly used percentage calculation for shopping, taxes, and tips.
Mode 2 — X is What % of Y?
Use this to find what percentage one number is of another. Examples: 45 is what percentage of 180? My salary is ₹42,000 — my rent is ₹12,000, what percentage of my salary is rent? I scored 378 out of 500, what percentage did I get? Enter both values and get the percentage relationship immediately.
Mode 3 — Percentage Increase / Decrease
Use this to find how much something changed as a percentage. Examples: My salary went from ₹40,000 to ₹46,000 — what is the percentage increase? A product price dropped from ₹1,200 to ₹960 — what is the percentage discount? Enter the original and new value; select increase or decrease. The calculator returns the exact percentage change.
Mode 4 — Marks Percentage
Use this for exam and test results. Enter the marks you scored and the maximum marks available. Works for any exam — Class 10 boards, Class 12 boards, JEE, NEET, university semesters, competitive exams. Enter 452 out of 600, or 67 out of 80, and get your exact percentage immediately.
Mode 5 — Find the Original Value
Use this to reverse a percentage change and find the starting value. Examples: A phone costs ₹17,000 after a 15% discount — what was the original price? A salary is ₹52,000 after a 30% hike — what was it before? Enter the final value and the percentage change, select increase or decrease, and get the original value instantly.
How to Use the Percentage Calculator
Simple steps to get your percentage answer in seconds using any of the five calculation modes.
Select the Right Calculation Mode
Look at the five tabs at the top of the calculator: "What is X% of Y?", "X is what % of Y?", "% Increase/Decrease", "Marks Percentage", and "Find Original". Choose the tab that matches your question. If you are not sure which mode to use, read the tab label as a question and see which one fits what you are trying to solve.
Enter Your Numbers
Type your values into the input fields. Each mode has clearly labelled fields — for example, "Marks Obtained" and "Total Marks" in the marks mode, or "Original Value" and "New Value" in the increase/decrease mode. Enter numbers only (no commas or symbols). Decimal numbers are supported for precise calculations.
Click Calculate
Press the "Calculate" button to get your result. The answer appears immediately along with the formula used — so you can verify the calculation and understand the method. For the percentage increase/decrease and find-original modes, make sure you have selected the correct toggle (Increase or Decrease) before calculating.
Copy or Clear Your Result
Use the "Copy Result" button to copy your answer to the clipboard for pasting into a document, message, or spreadsheet. Use the "Clear" button to reset the fields and calculate a new value in the same mode, or switch to a different tab for a different type of percentage calculation.
Worked Examples for All Five Modes
Real-world examples showing exactly how each calculation mode works and how to interpret the result.
Mode 1 — What is 18% of ₹4,500? (GST Calculation)
Formula: (18 ÷ 100) × 4,500 = 0.18 × 4,500 = ₹810
Use case: A product costs ₹4,500 before 18% GST. The tax amount is ₹810, making the final price ₹5,310.
Mode 2 — 378 is What % of 500? (Exam Result)
Formula: (378 ÷ 500) × 100 = 0.756 × 100 = 75.6%
Use case: A student scored 378 marks in a 500-mark exam. Their percentage is 75.6% — a First Division result.
Mode 3 — Salary Hike from ₹35,000 to ₹42,000
Formula: ((42,000 − 35,000) ÷ 35,000) × 100 = (7,000 ÷ 35,000) × 100 = 20% increase
Use case: An employee's salary increased from ₹35,000 to ₹42,000. This represents a 20% raise.
Mode 4 — Class 12 Board Result (452 out of 600)
Formula: (452 ÷ 600) × 100 = 75.33%
Use case: A student scored 452 marks across all subjects in Class 12 boards where the maximum is 600. Their overall percentage is 75.33%.
Mode 5 — Find Original Price Before 20% Discount (Final Price ₹1,600)
Formula: 1,600 ÷ (1 − 20/100) = 1,600 ÷ 0.80 = ₹2,000
Use case: A product is selling for ₹1,600 after a 20% discount. The original MRP was ₹2,000.
Quick Reference — Common Percentage Conversions
| Percentage | Decimal | Fraction | Of 1,000 | Of 500 |
|---|---|---|---|---|
| 1% | 0.01 | 1/100 | 10 | 5 |
| 5% | 0.05 | 1/20 | 50 | 25 |
| 10% | 0.10 | 1/10 | 100 | 50 |
| 12.5% | 0.125 | 1/8 | 125 | 62.5 |
| 15% | 0.15 | 3/20 | 150 | 75 |
| 18% | 0.18 | 9/50 | 180 | 90 |
| 20% | 0.20 | 1/5 | 200 | 100 |
| 25% | 0.25 | 1/4 | 250 | 125 |
| 33.33% | 0.333 | 1/3 | 333.3 | 166.7 |
| 50% | 0.50 | 1/2 | 500 | 250 |
| 75% | 0.75 | 3/4 | 750 | 375 |
| 100% | 1.00 | 1/1 | 1,000 | 500 |
The Complete Guide to Percentage Calculations — Formulas, Uses, and Real-World Examples
Percentages are one of the most universally used forms of mathematics — appearing in exam results, GST bills, salary negotiations, EMI calculations, discount shopping, investment returns, and statistical data every single day. Yet many people reach for a calculator the moment any percentage question arises because the relationships between percentage, decimal, fraction, and base value are not always intuitive. This guide explains every type of percentage calculation clearly, with formulas and examples for each.
What Is a Percentage?
A percentage is a way of expressing a number as a fraction of 100. The word itself comes from the Latin "per centum," meaning "out of one hundred." When you say 45%, you mean 45 out of every 100, or the fraction 45/100, or the decimal 0.45. Percentages are useful because they allow fair comparison between quantities of different sizes — saying "she scored 85%" is more meaningful than "she scored 340 out of 400" when comparing across different tests with different maximum marks.
The Three Core Percentage Relationships
Every percentage problem is a variation of one equation: Percentage = (Part ÷ Whole) × 100. This one relationship generates three different calculations depending on which value is unknown. If you know the percentage and the whole, you find the part: Part = (Percentage ÷ 100) × Whole. If you know the part and the whole, you find the percentage: Percentage = (Part ÷ Whole) × 100. If you know the part and the percentage, you find the whole: Whole = Part ÷ (Percentage ÷ 100).
Recognising which two of the three values you already have immediately tells you which formula to use. This is the most fundamental percentage insight — most confusion about percentages dissolves once you identify clearly what you know and what you are looking for.
How to Calculate Percentage Increase and Decrease
Percentage change is calculated as: ((New Value − Original Value) ÷ Original Value) × 100. If the result is positive, it is a percentage increase. If negative, it is a percentage decrease. For example, if petrol prices rise from ₹95 to ₹108 per litre, the change is ((108 − 95) ÷ 95) × 100 = 13.68% increase. If a stock falls from ₹2,400 to ₹1,920, the change is ((1,920 − 2,400) ÷ 2,400) × 100 = −20%, a 20% decrease.
A common error is dividing by the new value instead of the original. Always divide by the starting (original) value. The percentage change from 100 to 150 is 50% (dividing by 100). But the percentage change from 150 back to 100 is −33.33% (dividing by 150, not 100) — which is why a 50% gain followed by a 50% loss does not return you to the starting value. This asymmetry matters in finance, business analysis, and exam questions.
Calculating Marks Percentage for Indian Exams
The standard formula is: Percentage = (Marks Obtained ÷ Total Marks) × 100. For Class 10 CBSE, the maximum total is typically 500 marks. For Class 12 CBSE, it is also 500 marks across five subjects. University semester exams vary — total marks may be 600, 700, or 800 depending on the number of subjects and their weightage. Always use the actual total marks from your marksheet, not an assumed figure.
For Indian board exams, standard grade divisions are: Distinction (75% and above), First Division (60–74%), Second Division (50–59%), and Pass (33–49%), though these thresholds vary by board and state. For competitive entrance exams like JEE Main, the percentage is calculated on the normalised score rather than raw marks, which is why official percentile and percentage figures may differ from your own raw marks calculation.
GST Calculations Using Percentages
India's Goods and Services Tax (GST) is a percentage applied to the base price of goods and services. The four main GST slabs are 5%, 12%, 18%, and 28%. To find GST amount: GST Amount = (GST Rate ÷ 100) × Base Price. To find total price including GST: Total = Base Price × (1 + GST Rate ÷ 100). To find the base price from a GST-inclusive price: Base = Total ÷ (1 + GST Rate ÷ 100).
For example, a restaurant bill of ₹2,360 includes 18% GST. The base price is 2,360 ÷ 1.18 = ₹2,000, and the GST component is ₹360. When comparing prices, always check whether quoted prices are inclusive or exclusive of GST — the difference is significant, particularly on high-value purchases like electronics, appliances, and vehicles.
Percentage in Finance — EMIs, Returns, and Discounts
In personal finance, percentages appear constantly. Interest rates on loans are annual percentages (EMI calculations involve percentage of outstanding principal). Investment returns are expressed as percentage of capital invested. Inflation is the annual percentage increase in price levels. Discount offers are percentage reductions from MRP. Understanding the base value is critical — "20% off" a ₹5,000 product saves ₹1,000, but "20% off" a ₹500 product saves only ₹100. The percentage is the same; the absolute amount depends entirely on the base.
Compound interest involves repeatedly applying a percentage to a changing base. If you invest ₹10,000 at 10% annual interest compounded annually, after year one you have ₹11,000. In year two, 10% is applied to ₹11,000 (not the original ₹10,000), giving ₹12,100. This compounding effect is why long-term investments grow faster than simple percentage calculations suggest — and why high-interest debt compounds dangerously.
Reverse Percentage — Finding the Original Value
When you know the final value after a percentage change and want to find the original, divide the final value by (1 + percentage/100) for an increase, or (1 − percentage/100) for a decrease. This is the reverse percentage calculation. It is particularly useful in shopping (finding MRP from a discounted price), taxation (finding pre-tax price from a tax-inclusive bill), and salary analysis (finding CTC before a percentage hike).
A frequent mistake is subtracting the percentage directly from the final value. If a ₹2,000 item has 25% added as tax, the pre-tax price is NOT 2,000 − 25% of 2,000 = 1,500. That would be correct only if the 25% was calculated on the final value — but tax is typically calculated on the base price. The correct reverse calculation is 2,000 ÷ 1.25 = ₹1,600. Always clarify whether the percentage was applied to the original or the final value before reversing.
Percentage vs. Percentage Points — A Critical Distinction
Percentage and percentage points are different things, and confusing them leads to significant errors. If interest rates rise from 4% to 6%, they have increased by 2 percentage points — but by 50% (because 2 is 50% of 4). News and financial reports frequently state "the rate increased by 2 percentage points" versus "the rate increased by 50%," both of which describe the same change from entirely different perspectives. The percentage points statement tells you the absolute change; the percentage statement tells you the relative change.
This distinction matters enormously in contexts like election results (Party A's vote share fell from 40% to 32% — a drop of 8 percentage points, or a 20% decline in their share), academic performance, and economic indicators. When reading any statistic involving percentages, confirm whether the stated change is in percentage points or as a percentage of the previous value.
Mental Maths Shortcuts for Quick Percentage Estimates
Several shortcuts make percentage estimation fast without a calculator. To find 10% of any number, move the decimal point one place left (10% of 3,750 = 375). To find 5%, halve the 10% result (5% of 3,750 = 187.5). To find 1%, move the decimal two places left (1% of 3,750 = 37.5). For 15%, add the 10% and 5% results (375 + 187.5 = 562.5). For 20%, double the 10% result (750). For 25%, divide by 4 (937.5).
These building-block calculations let you quickly estimate most common percentages in your head. For GST at 18%, find 10% + 8% (which is 10% − 2%, or 10% − one-fifth of 10%). For 12%, find 10% + 2%. For 28%, double the 14% (which is 10% + 4%). Practising these shortcuts reduces reliance on a calculator for everyday transactions like splitting bills, estimating discounts, or checking whether a quoted GST amount is correct.
Frequently Asked Questions
Common questions about percentage calculations, formulas, and everyday use cases.