You scored marks in five subjects, your college tracks attendance out of total classes, and your manager just told you about a raise. All three questions use the word "percentage," but they're not the same calculation. Mix them up and you'll get a number that looks right and isn't.

Here's each one worked out with real numbers, plus the one mistake almost every student makes with marks percentage.

Quick answer: Marks percentage = (total scored ÷ total maximum) × 100. Attendance percentage = (classes attended ÷ classes held) × 100. Salary hike percentage = ((new salary − old salary) ÷ old salary) × 100. All three can be checked in seconds with the percentage calculator — "What %" mode for the first two, "% Change" mode for the third.

Marks Percentage: Add the Totals First, Don't Average the Subjects

Say you scored 78 out of 100 in Maths, 65 out of 80 in Physics, and 142 out of 200 in English. Your total scored is 78 + 65 + 142 = 285. Your total maximum is 100 + 80 + 200 = 380. Divide: 285 ÷ 380 = 0.75. Multiply by 100, and you get 75%.

The mistake: working out each subject's percentage separately (78%, 81.25%, 71%) and then averaging those three numbers. That gives 76.75% — close, but wrong, because it treats every subject as equally weighted regardless of how many marks it was actually worth. The Physics paper is worth less than the English paper, so it shouldn't count the same in your average. Add the raw totals first, then divide once.

On the percentage calculator, this is "What %" mode: enter your total scored marks as the part, your total maximum marks as the whole.

CBSE Class 10: the "best of five" percentage students actually use

If you've searched for a CBSE percentage calculator, here's the part most pages skip: CBSE itself does not issue an official aggregate percentage for Class 10 anymore — a 2024 board notice says no overall division or aggregate marks are awarded. The "best of five" percentage you see students quote is something students, coaching centres, colleges, and employers calculate themselves, not a number CBSE hands out.

The common method: out of six subjects, drop your lowest-scoring one (English almost always stays), add the remaining five, and divide by 500 — not 600. Score 97, 92, 94, 96, and 98 in five subjects and your total is 477. That's 477 ÷ 500 × 100 = 95.4%. Swap in a weaker sixth subject and the number changes, which is exactly why colleges set their own rule for which five count — check the specific college or employer's policy rather than assuming one standard applies everywhere.

Attendance Percentage: The Exact Math for "How Many More Classes?"

Most Indian colleges and universities set a minimum attendance requirement before you can sit the final exam — 75% is the figure most commonly cited, though the exact number and the appeal process for falling short vary by institution, so check your own college's rule rather than assuming.

Say you've attended 125 out of 180 classes held so far. That's 125 ÷ 180 × 100 = 69.4% — below the usual 75% line. The real question isn't "what's my percentage," it's "how many classes in a row do I need to attend to fix this?"

Here's the algebra, assuming you attend every class from now on and no more classes get added beyond what's conducted: let x be the number of additional classes you need. You want (125 + x) ÷ (180 + x) = 0.75. Solve it: 125 + x = 0.75(180 + x) → 125 + x = 135 + 0.75x → 0.25x = 10 → x = 40. Check it: (125 + 40) ÷ (180 + 40) = 165 ÷ 220 = 75%. Forty classes, not a guess.

You don't need to do that algebra by hand every time. Punch your attended and total numbers into "What %" mode on the calculator, then try adding 1 to both numbers repeatedly (or jump by 10s) until the result crosses 75% — it takes a few seconds either way.

Salary Hike Percentage: Old Number First, Always

Your salary moved from ₹45,000 to ₹52,000 a month. Whether you call this a salary hike percentage calculator or a salary percentage increase calculator, the formula is the same: ((52,000 − 45,000) ÷ 45,000) × 100 = (7,000 ÷ 45,000) × 100 = 15.6%.

Notice the old salary is the denominator, not the new one. Divide by the new salary instead and you'd get 13.5% — a different, wrong answer. This works identically for annual CTC figures; just don't mix an annual old number with a monthly new one.

On the calculator, this is "% Change" mode: old salary goes in as the Initial Value, new salary as the Final Value. If your new number is lower than your old one — a pay cut, or last year's bonus not repeating — the tool labels the result "Decrease" instead of "Increase," automatically.

Reverse Percentage: You Know the Result, Not the Starting Number

Sometimes the number you have is the end result, and you need to work backward. A shirt costs ₹850 after a 15% discount — what was the original price before the discount?

Final price = Original × (1 − discount rate), so Original = Final ÷ (1 − discount rate). That's 850 ÷ (1 − 0.15) = 850 ÷ 0.85 = ₹1,000. Check it: 1,000 minus 15% is 850. This is "Reverse %" mode on the calculator — you give it the result and the rate, and it solves for the number you started with, which none of the other three modes do.

CGPA to Percentage: Multiply by Your Board's Factor

None of the four formulas above will convert a CGPA correctly — CGPA isn't a part-to-whole ratio, it's a grade-point average, and turning it into a percentage needs a multiplier set by your specific board or university, not division. The percentage calculator has a fifth mode for exactly this: "CGPA to %."

Enter your CGPA, then enter the multiplier — 9.5 is the figure commonly used for CBSE. A CGPA of 8.4 gives 8.4 × 9.5 = 79.8%. That multiplier isn't universal, though: other boards and universities set their own factor, and some don't offer an official conversion at all. Check your own institution's rule before you enter anything into the multiplier box.

One Calculator, Five Different Questions

The formulas look similar because they're all variations on "part versus whole" or "one value times another," but they answer different questions. Marks percentage tells you what you scored against a fixed maximum. Attendance percentage tells you where you stand against a rule with a deadline. Salary hike percentage tells you how much something grew relative to where it started. Reverse percentage works the other direction entirely — from the answer back to the question. CGPA to percentage converts a grade-point average using a board-specific factor, not a ratio at all. Confusing which mode to use is the actual source of most "wrong" percentage answers — not bad arithmetic.

Frequently asked questions

Does the percentage calculator convert CGPA to percentage?

Yes. Select "CGPA to %" mode, enter your CGPA, and enter the multiplier your board or university uses (commonly 9.5 for CBSE). It multiplies the two numbers to give your percentage. Confirm your own institution's multiplier first, since it isn't the same everywhere.

Is my data saved when I use the calculator?

No. It runs entirely in your browser, needs no account or login, and doesn't store or send your numbers anywhere.

Does the salary hike formula work for annual CTC, or only monthly pay?

Either, as long as you don't mix them — compare old annual CTC to new annual CTC, or old monthly pay to new monthly pay, not one of each.

What if my percentage change comes out negative?

It means a decrease. On the calculator's "% Change" mode, a negative result is labeled "Decrease" automatically rather than shown as a plain negative number.

Is 75% attendance the rule at every college?

No. It's the figure most often cited for Indian colleges and universities, but the exact minimum and what happens if you fall short differ by institution — check your own college's attendance policy.

Does CBSE officially calculate a "best of 5" percentage for Class 10?

No. A 2024 CBSE notice states the board doesn't award an overall division or aggregate for Class 10 anymore. The best-of-five, out-of-500 percentage is a calculation students, coaching centres, colleges, and employers do themselves — not an official CBSE figure.