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Expensico

Percentage Calculator

Solve every everyday percentage question: X% of Y, what percent X is of Y, percentage change, and increase or decrease by a percentage.

Runs in your browser. Everything you enter stays on your device. Nothing is sent to a server.

How to use the Percentage Calculator

  1. Find the question that matches yours.
  2. Type your numbers into its boxes.
  3. The answer updates as you type.

Percentage formulas

  • X% of Y = X ÷ 100 × Y
  • A is what % of B = A ÷ B × 100
  • Percentage change = (new − old) ÷ |old| × 100
  • Increase by X% = value × (1 + X/100); decrease by X% = value × (1 − X/100)
  • Reverse percentage (original before an X% increase) = result ÷ (1 + X/100)

Common pitfalls

  • A 50% fall followed by a 50% rise doesn't get you back where you started: 100 → 50 → 75.
  • “Percent” and “percentage points” differ. A rate moving from 6% to 8% is a 2 percentage-point rise but a 33% increase.
  • To remove tax or a mark-up, divide rather than subtract — see the GST calculator.

Example

  • 15% of 2,400 = 360.
  • Marks: 360 out of 2,400 is 15%.
  • A price going from ₹80 to ₹100 is a 25% increase; from ₹100 back to ₹80 is a 20% decrease.

Frequently asked questions

How do I calculate percentage marks?

Divide marks obtained by total marks and multiply by 100. Use the second row: enter your marks and the total.

Why is percentage change undefined from zero?

Any change from zero is an infinite percentage, so the calculator shows a dash. Describe it as an absolute change instead.

Is what I enter stored or sent anywhere?

No. Calculations and processing happen in your browser. Nothing you type is sent to our servers. Some tools remember your last input in this browser's local storage for convenience; you can clear it at any time.