Percentage Calculator — Free Online
One calculator for the five percentage questions people actually search for: converting marks to a percentage with the matching grade, working out a price or salary increase, finding X% of a number, seeing one figure as a share of another, and converting between percentage and CGPA. Every result shows the formula it used, so you can check the working.
What do you want to calculate?
15% of 4,800
720
4,800 × 15 ÷ 100 = 720
Marks grading reference
- A+ / A1 — Excellent80%+
- A / A2 — Very good70%+
- B — Good60%+
- C — Average50%+
- D — Below average40%+
- E — Weak pass33%+
- F — Fail0%+
Formulas used
- X% of Y — Y × X ÷ 100
- X is what % of Y — X ÷ Y × 100
- % change — (new − old) ÷ old × 100
- Marks % — obtained ÷ total × 100
- CGPA ⇄ % — percentage ÷ 9.5 (universities differ: some use CGPA ÷ 4 × 100)
How to use the Percentage Calculator
- 1
Pick the question
Choose the mode that matches what you need — “X% of a number”, “is what %”, “increase / decrease”, “marks to percentage” or “percentage ⇄ CGPA”.
- 2
Type your two numbers
The labels change with the mode, so it is always obvious which value goes where. Decimals, commas-free numbers and large figures all work.
- 3
Read the answer & the formula
The result appears instantly with the arithmetic spelled out, plus extras like the grade band, the mark difference or the conversion in the other direction.
Why use Tools Stars for this?
- Five calculators in one page — no hunting for the right tool
- Marks mode adds the grade band and an estimated CGPA
- Increase / decrease mode shows the direction and the raw difference
- Both CGPA directions at once: percentage ÷ 9.5 and CGPA × 9.5
- The exact formula is printed under every answer so you can verify it
- One-tap copy of the result for forms, WhatsApp and emails
- Built-in grading reference table for boards and universities
Frequently asked questions
How do I calculate my marks percentage?
Divide the marks you obtained by the total marks, then multiply by 100. For example 742 out of 1,100 is 742 ÷ 1100 × 100 = 67.45%. Choose the “Marks to percentage” mode and it also tells you the grade band, how many marks you lost, and the rough CGPA equivalent.
What is the formula for percentage increase or decrease?
(new value − old value) ÷ old value × 100. A positive result is an increase, a negative one is a decrease. Going from 4,000 to 4,800 is +20%; going from 4,800 back to 4,000 is −16.67%, which is why the two directions of the same change are not mirror images.
How do I convert a percentage to CGPA?
The most widely used rule in South Asia is percentage ÷ 9.5, so 85% ≈ 8.95 CGPA on a 10-point scale. Reversed, CGPA × 9.5 gives the percentage. Note that many universities publish their own conversion — some use CGPA ÷ 4 × 100 on a 4.0 scale, others use a fixed lookup table — so always confirm with your institution for official transcripts.
What is 15% of 4,800?
672. The rule is: multiply the number by the percentage and divide by 100 (4,800 × 15 ÷ 100). A quick mental shortcut is to find 10% (480), then half of that for 5% (240), and add them together.
Why does my division by zero show an error?
A percentage is always a share of something, so the second value cannot be zero — 5 out of 0 has no meaning. The calculator says so instead of showing “Infinity” or “NaN”, which is what a plain calculator would print.
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