Everyday Percentage Calculator

Handle the percentage calculations that come up every day, from checking a discount to comparing prices or measuring an increase. Choose a mode and enter two numbers to get an instant result.

Percentage details

Result

300

15% of 2000

Three different questions, three different formulas

Most percentage mistakes come from applying the wrong one of these three. They look similar and answer entirely different questions.

The three modes
QuestionFormulaExample
What is 15% of 2,400?value x percent / 100360
360 is what percent of 2,400?part / whole x 10015%
From 2,400 to 2,760, what changed?(new - old) / old x 100+15%

Why a rise and a fall of the same percentage do not cancel

A percentage change is always measured against its own starting point, so the base moves between the two steps. A price that rises 20% and then falls 20% does not return to where it began -- it ends 4% lower, because the fall is taken from the larger figure.

The same asymmetry explains why recovering a loss takes a larger percentage than the loss itself. A 50% fall needs a 100% rise to get back to level.

The rise needed to recover a fall
FallRise needed to recover
10%11.1%
20%25.0%
33.3%50.0%
50%100.0%
75%300.0%

Percentage points are not percent

A rate moving from 8% to 10% has risen by two percentage points, which is a 25% increase. Both statements are correct and they describe very different magnitudes, which is why interest rates and inflation figures are quoted in percentage points.

When reading a claim about a rate that has changed, check which of the two is being reported before drawing a conclusion from it.

More everyday tools

Frequently asked questions

Divide the percentage by 100, then multiply it by the amount. For example, 15% of 2,000 is 0.15 multiplied by 2,000, which equals 300.

Subtract the original value from the new value, divide by the absolute original value, and multiply by 100. A positive result is an increase and a negative result is a decrease.

Subtract the old value from the new one, divide by the old value, and multiply by 100. From 200 to 250 that is 50 divided by 200, which is 25%. Dividing by the new value instead is the usual error and understates the rise.

Divide the part by the whole and multiply by 100. Thirty out of forty is 30 divided by 40, which is 0.75, or 75%. Getting the two the wrong way round gives 133%, which is the tell that they have been swapped.

Multiply the price by the discount percentage to get the saving, then subtract it. Twenty percent off Rs. 2,500 is a saving of Rs. 500, leaving Rs. 2,000. To go the other way, divide the sale price by 0.8 to recover the original.

Because each percentage is taken against a different base. A 50% fall from 100 leaves 50, and getting from 50 back to 100 is a rise of 50 on a base of 50 - which is 100%. Percentage rises and falls of the same size never cancel out.

A move from 5% to 7% is a rise of two percentage points, but a rise of 40 percent. Both are correct and they describe different things, which is why interest rates and tax rates are usually discussed in percentage points to avoid the ambiguity.

Divide rather than subtract. If Rs. 1,180 already includes an 18% addition, the original is 1,180 divided by 1.18, which is Rs. 1,000. Subtracting 18% from Rs. 1,180 gives Rs. 967.60 and is wrong, because the 18% was calculated on the smaller base.