Tip and bill split calculator

The formula

$$\text{each} = \frac{B\left(1 + \frac{p}{100}\right)}{k}$$

$B$ is the bill, $p$ the tip percentage and $k$ the number of people.

Where it comes from

A tip of $p$ percent is $p/100$ of the bill:

$$\text{tip} = B \cdot \frac{p}{100}$$

The total is the bill plus the tip. Factoring out $B$ shows the shortcut: multiply the bill by $1 + p/100$, so 1.18 for an 18% tip:

$$\text{total} = B + B \cdot \frac{p}{100} = B\left(1 + \frac{p}{100}\right)$$

Splitting evenly divides the total by the number of people.

Worked example

An $86.40 bill, 18% tip, three people:

$$\text{tip} = 86.40 \times 0.18 = 15.55, \qquad \text{each} = \frac{86.40 \times 1.18}{3} = 33.98$$

Mental shortcuts

• 10%: move the decimal point one place left, so $86.40 becomes $8.64.
• 20%: double that, $17.28.
• 15%: 10% plus half of it, $8.64 + $4.32 = $12.96.

Watch out for

• Tip on the pre-tax amount if that’s the custom where you are. Enter the bill before tax.

Last checked November 11, 2026