RubanTools

Percentage Calculator

Three tools in one - find a percentage of a number, calculate what % one value is of another, or find the percentage change between two numbers.

of
of

Every Percentage Problem, Solved

One page covers all three ways you'll ever need to work with percentages.

Three Modes in One

Find a value, find a rate, or measure change - every common percentage calculation is covered without switching to a different tool.

Decimal Precision

Results show up to 4 decimal places where needed, with trailing zeros stripped. Useful for exam scores, financial rates, and GST amounts.

Instant Results

The result updates as you type - no button press needed. The formula is shown alongside the answer so you can verify the logic.

Three Steps to Your Answer

01
Choose a Mode

Select one of the three tabs at the top depending on what you want to calculate.

02
Enter Your Numbers

Type the two values into the input fields. Decimals are supported in all modes.

03
Read the Result

The answer appears instantly along with the full formula so you understand the calculation.

Everyday Situations

Calculate GST or discount on a purchase price
Find the percentage you scored in an exam
Check how much a salary or price has increased
Calculate commission, tip, or bonus amount
Find a student's percentage from marks obtained
Determine percentage share in a team budget

Percentage Calculator Find %, Of %, and % Change

Percentages are one of the most universally used mathematical concepts in daily life, finance, education, and business. The term "percent" comes from the Latin "per centum," meaning per hundred. First systematically used in European commerce in the 15th century, percentages became foundational to banking, taxation, and statistics. In India, percentage calculations feature prominently in competitive examinations, salary negotiations, GST computations, and academic grading systems.

Three Types of Percentage Problems

This calculator handles the three most common percentage scenarios: (1) Finding X% of a given number - used for calculating discounts, GST amounts, or exam scores; (2) Finding what percentage one number is of another - used for calculating marks percentage in CBSE or university exams, or profit margins; (3) Finding the percentage increase or decrease between two values - used for comparing monthly sales, inflation rates, or salary hikes. Each calculation type is presented with a clear formula and step-by-step explanation.

Exam Relevance and Everyday Use

Percentage questions appear in virtually every competitive exam in India - SSC CGL, UPSC CSAT, CAT, Bank PO, IBPS, and NEET entrance exams all include percentage-based problems. RBI monetary policy reports, SEBI market statistics, and CBSE mark sheets all express data as percentages. Whether you are calculating a 18% GST on a bill, finding out what percentage marks you scored in Class 12, or working out a 12% salary hike, this tool provides instant and accurate results.

Frequently Asked Questions

% of Number - enter a percentage and a number to find that percentage of it (e.g. 15% of 200 = 30).
X is what % of Y - enter two numbers to find what percentage the first is of the second (e.g. 30 is 15% of 200).
% Change - enter an original value and a new value to find the percentage increase or decrease between them.

Yes. All three modes accept decimal numbers (e.g. 12.5% of 340 = 42.5). Results are displayed to up to 4 decimal places, with trailing zeros removed automatically.

Percentage change measures the relative difference between an original value and a new value. The formula is: ((New − Original) ÷ |Original|) × 100. A positive result means an increase; a negative result means a decrease.

The percentage change formula divides by the original value. Division by zero is mathematically undefined, so an original value of zero produces no meaningful result and the calculator will show an error.

Yes. All three modes run entirely in JavaScript in your browser. No data is ever sent to any server - your numbers stay completely private.