Calculators

Percentage Calculator

Work out a percentage of a number, what share one number is of another, or the change between two values.

What do you want to work out?What do you want to work out?
%
Result36015% of 2,400

How it works

Every percentage question is one of three shapes: finding a part when you know the share, finding the share when you know the part, or comparing two values. The word percent just means per hundred, so all three reduce to a division and a multiplication by 100.

X% of Y = X ÷ 100 × Y · X as % of Y = X ÷ Y × 100 · change = (new − old) ÷ |old| × 100
X
The part, or the percentage, depending on the question
Y
The whole you are taking a share of
old
The starting value when measuring change
new
The ending value when measuring change

Worked example

A ₹2,400 bill with a 15% service charge.

  1. 1Convert the percentage to a decimal: 15 ÷ 100 = 0.15
  2. 2Multiply by the amount: 0.15 × 2,400 = 360
  3. 3Add it back for the total: 2,400 + 360 = 2,760

The service charge is ₹360, making the bill ₹2,760.

Frequently asked questions

How do I work out a percentage in my head?

Find 10% by moving the decimal point one place left, then build from there. 10% of 840 is 84, so 5% is 42 and 15% is 126. For a rough 18% tip, take 10%, add half of it again, then a bit more. Most everyday percentages are reachable from 10% with one or two easy steps.

Why is a 50% rise followed by a 50% fall not back where you started?

Because the second percentage applies to a larger number. Rising from 100 by 50% gives 150; falling by 50% from 150 takes away 75, leaving 75. Percentage changes are always relative to whatever the value is at that moment, which is why they do not simply cancel out.

What is the difference between percentage points and percent?

If an interest rate goes from 4% to 6%, that is a rise of two percentage points but a 50% increase. Confusing the two makes small changes sound dramatic or large ones sound trivial. Use percentage points when comparing two percentages, and percent when describing relative change.

How do I reverse a percentage to find the original price?

Divide rather than subtract. If an item cost ₹590 after an 18% GST, the original is 590 ÷ 1.18 = ₹500, not 590 − 18%. The common mistake is taking the percentage off the final figure, which gives a number that is always slightly too low.

Can a percentage be more than 100?

Yes, whenever the part is larger than the whole you are comparing it to. Revenue tripling is a 200% increase, and 150 is 150% of 100. Percentages above 100 only look odd when the whole is a genuine maximum, such as a share of a fixed total.

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