Percentage Calculator — Marks, Discounts & Change

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Three percentage jobs in one tool: find a percent of a number, find what percent one number is of another, and measure percentage change.

Percent (%)

Of the number

The part

Of the whole

From (old)

To (new)

How to use this tool

1. Pick the tab that matches your question — the tool switches instantly.
2. Type your numbers; results appear as you type. No submit button needed.
3. Use Reset all to clear every field.

Example

Marks: you scored 45 out of 60 — the What percent tab gives 45 ÷ 60 × 100 = 75%.
Discount: a 2,500 taka shirt at 30% off — the Percent of a number tab gives 30% of 2,500 = 750 taka saved.
Growth: your study hours went from 52 to 65 a month — the Percent change tab gives +25%.

The formula

part ÷ whole × 100 = percentage   |   change = (new − old) ÷ |old| × 100

What the result means

A percentage is just a fraction out of 100 — it lets you compare things of different sizes fairly. Percentage change always compares against the old value, which is why a 50% loss needs a 100% gain to recover.

Frequently asked questions

When do I use which tab?

Percent of a number answers “what is 35% of 80?”. What percent answers “45 is what percent of 60?”. Percent change answers “how much did it grow or shrink from old to new?”

Why is the percentage-change formula using the absolute old value?

So that changes from negative starting numbers still point in the right direction. For everyday positive numbers it behaves exactly as you expect.

Is a 100% increase the same as doubling?

Yes. And a 50% decrease is not undone by a 50% increase — 100 → 50 → 75. Percentages are not symmetric going down and up.

Does this tool save my numbers?

No. Everything is computed in your browser and disappears when you leave the page.

Can I use decimals and negative numbers?

Yes — decimals anywhere, and negatives work everywhere except as the whole or the old value in change calculations.

More tools from Scholar Bay

GPA CalculatorOne semester, course by courseCGPA CalculatorAll semesters combinedFinal Grade CalculatorMarks needed in your final examAttendance CalculatorCan you skip that class?

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• Scholar Bay — the university island where this tool lives.
• The Main Island — drive the boat, explore the whole world.
• The 90s Kids Island — where most of us started school.

Privacy & data: this tool runs entirely in your browser — nothing you type is uploaded, saved or sent anywhere. · Disclaimer: results are for guidance only; always confirm important academic decisions with your university or official documents. · Privacy Policy · Disclaimer