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Percentage Calculator – Marks, Increase, Decrease and More

Five everyday percentage calculations on one page, each with the working shown: X% of Y, what percent, percentage change, adding or removing a percentage, and marks percentage.

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How to use the percentage calculator

  1. Pick the card that matches your question — each one answers a different kind of percentage problem.
  2. Type your numbers. The answer updates instantly as you type.
  3. Read the result in large text and the working underneath, so you can check it or copy it into your notes.
  4. Tap Copy to copy the answer, or Reset examples to bring back the sample numbers.

The five percentage formulas

1. What is X% of Y?

Result = X ÷ 100 × Y

Example: 18% GST on ₹5,000 = 18 ÷ 100 × 5,000 = ₹900.

2. X is what percent of Y?

Percentage = X ÷ Y × 100

Example: you saved ₹4,500 out of a salary of ₹30,000. 4,500 ÷ 30,000 × 100 = 15%.

3. Percentage increase or decrease

Change % = (New − Old) ÷ Old × 100

Example: rent went up from ₹12,000 to ₹13,200. (13,200 − 12,000) ÷ 12,000 × 100 = 10% increase. A negative answer means a decrease.

4. Add or subtract a percentage

New value = Value × (1 ± Percentage ÷ 100)

Example: a price of ₹1,000 plus 18% = 1,000 × 1.18 = ₹1,180. A salary of ₹50,000 minus 10% = ₹45,000.

5. Marks percentage

Percentage = Marks obtained ÷ Total marks × 100

Example: 432 out of 500 = 432 ÷ 500 × 100 = 86.4%. For several subjects, add up all the marks you obtained and all the maximum marks first, then divide.

Common mistakes to avoid

  • Dividing by the wrong number. Percentage change is always measured against the old (starting) value.
  • Adding percentages that apply one after another. A 50% discount plus an extra 20% off is a 60% discount, not 70%. Our discount calculator shows this clearly.
  • Removing tax by subtracting the percentage. To take 18% GST out of ₹1,180, divide by 1.18 — don’t subtract 18%. The GST calculator does this for you.

Example: percentage across several subjects

For a board exam with five subjects, add up all the marks first:

SubjectMarksOut of
English78100
Mathematics92100
Science85100
Social Science88100
Hindi or Bengali89100
Total432500

Percentage = 432 ÷ 500 × 100 = 86.4%. Don’t average the five percentages if the subjects have different maximum marks — always divide total marks obtained by total maximum marks.

Who uses a percentage calculator

  • Students working out marks percentage for admission forms and scholarships.
  • Shoppers checking discounts and price rises.
  • Employees checking a salary hike or the tax deducted.
  • Small business owners calculating margins, GST and price changes.

For exact age on an exam cut-off date, try the age calculator.

Frequently asked questions

How do I calculate percentage of marks?

Divide the marks you got by the total marks and multiply by 100. For 432 out of 500: 432 ÷ 500 × 100 = 86.4%.

How do I find X% of a number?

Divide the percentage by 100 and multiply by the number. 25% of 1,200 = 25 ÷ 100 × 1,200 = 300.

How do I calculate percentage increase?

Subtract the old value from the new value, divide by the old value and multiply by 100. From 400 to 500: (500 − 400) ÷ 400 × 100 = 25% increase.

Is a 50% increase followed by a 50% decrease the same as no change?

No. 100 increased by 50% is 150, and 150 decreased by 50% is 75 — a 25% loss overall. Each percentage applies to a different starting number.

How do I convert CGPA to percentage?

It depends on your board or university. CBSE has used a multiplier of 9.5 (percentage = CGPA × 9.5), but many universities use their own formula. Always use the conversion printed on your marksheet or given by your institution.

What is the difference between percent and percentage points?

If an interest rate goes from 8% to 10%, it rose by 2 percentage points, but by 25% in relative terms (2 ÷ 8 × 100). News reports often mix these up.

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