Skip to content

Percentage Calculator

Find X% of a number, what percent one number is of another, the percentage change between two values, or increase and decrease a number by a percentage, with the working shown.

Formulas last reviewed: September 2026

Disclaimer: Results are calculated with standard formulas and are meant for learning and quick checks. Please double-check important work, especially anything used for exams, engineering, finance or safety.

Percentages made simple

A percentage is a number out of 100. It is used for discounts, marks, interest rates, GST, salary hikes and almost every comparison in daily life. This calculator handles the six most common questions: what is X% of Y, X is what percent of Y, X is Y% of what number, percentage change, increase by a percentage and decrease by a percentage.

Each answer comes with its working so you can learn the method and check it by hand.

How it is calculated

X% of Y = X ÷ 100 × Y
Percent change = (new − old) ÷ |old| × 100
Increase by P% = value × (1 + P ÷ 100)

Worked example

Common questions

20% of 150
30
Change from 80 to 100
+25%
₹2,000 increased by 18% GST
₹2360
₹2,000 reduced by 25% discount
₹1500

Percentage points vs percent change

If an interest rate rises from 6% to 8%, it has gone up by 2 percentage points, but by 33.3% in relative terms. Newspapers and reports mix the two, so always check which one is meant.

  • Increase then decrease by the same percentage does not return you to the start: 100 up 10% is 110, and 110 down 10% is 99.
  • To find the original price before a discount, divide by (1 − discount).

Frequently asked questions

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply by the number. For example 15% of 240 is 0.15 × 240 = 36.

How do I find the percentage increase between two numbers?

Subtract the old value from the new value, divide by the old value and multiply by 100. A rise from 50 to 65 is 30%.

How do I remove GST or a discount to find the original price?

Divide the final price by one plus the rate for GST (for example by 1.18 for 18%), or by one minus the discount for a sale price.

Why is a percentage decrease not the reverse of an increase?

Because the percentage is taken from a different base each time. A 50% rise from 100 gives 150, but a 50% fall from 150 gives only 75.