How do I calculate what is X% of Y?

Multiply Y by X and divide by 100. For example, 20% of 150 is (20 × 150) ÷ 100 = 30. The calculator updates instantly as you type.

How do I find what percentage one number is of another?

Divide the first number by the second and multiply by 100. For example, 30 is what percent of 150? (30 ÷ 150) × 100 = 20%.

How is percentage increase or decrease calculated?

Subtract the old value from the new value, divide by the old value, then multiply by 100. From 80 to 100 is ((100 − 80) ÷ 80) × 100 = 25% increase.

How do I calculate a tip and split the bill?

Multiply the bill by the tip percentage to get the tip, add it to the bill, then divide by the number of people. An 18% tip on a $60 bill split three ways is $23.60 each.

How do I add or remove VAT/GST from a price?

To add VAT, multiply the net price by (1 + rate/100). To remove VAT from a gross price, divide by (1 + rate/100). For 20% VAT, $100 net becomes $120 gross, and $120 gross has a $100 net value.

Percentage Calculator — Tip, Discount & VAT

How to calculate percentages

A percentage is simply a fraction of 100. The word "percent" literally means "per hundred", so 25% is the same as 25 out of 100, or the decimal 0.25. Almost every everyday percentage question — a tip at dinner, a sale price, a tax line on a receipt, or the growth of your savings — comes down to one of a handful of small formulas. This Percentage Calculator bundles the six most common ones into a single tool that runs entirely in your browser, so nothing you type is ever sent to a server.

Finding X% of a number

To find a percentage of a value, multiply the value by the percentage and divide by 100. The formula is result = (X × Y) ÷ 100. For example, to find 20% of 150 you compute (20 × 150) ÷ 100 = 30. A handy shortcut is to move the decimal: 10% of any number is that number with the decimal shifted one place left, so 10% of 150 is 15, and 20% is just double that.

What percentage one number is of another

When you know two numbers and want the relationship between them, divide the part by the whole and multiply by 100: percent = (X ÷ Y) × 100. If you scored 30 out of a possible 150, that is (30 ÷ 150) × 100 = 20%. This is the formula behind test scores, completion rates and market share. Percentages are reversible too: if 30 is 20% of a number, divide to find the whole, 30 ÷ 0.20 = 150.

Percentage increase and decrease

To measure change between an old and a new value, use change = ((new − old) ÷ old) × 100. Going from 80 to 100 is a 25% increase, while going from 100 to 80 is a 20% decrease. Notice the percentages are not the same in both directions — that is because the base value changes. This catches a lot of people out with stock prices: a 50% drop needs a 100% gain to recover.

Tips and splitting the bill

The tip is the bill multiplied by the tip rate: tip = bill × (rate ÷ 100). Add it to the bill for the grand total, then divide by the number of diners for the per-person share. An 18% tip on a $60 bill is $10.80, giving a $70.80 total, or $23.60 each when split three ways. To tip roughly 20% fast, take 10% (shift the decimal) and double it.

Discounts and sale prices

A discount reduces the original price: sale = original × (1 − discount ÷ 100). A 25% discount on a $120 item saves $30 and leaves a $90 sale price. Stacked discounts multiply rather than add — 20% off then a further 10% off is not 30% off, it is 0.8 × 0.9 = 0.72, so 28% off.

Adding and removing VAT or GST

To add tax to a net price, multiply by (1 + rate ÷ 100); a $100 net price with 20% VAT becomes $120. To work backwards from a gross (tax-inclusive) price, divide by the same factor: $120 ÷ 1.20 = $100 net, with $20 of tax. A common error is subtracting the rate from the gross price — that under-removes the tax, because the tax was calculated on the smaller net figure. Everything here is computed locally in your browser, and the recent-calculations list is stored only on your own device.