Sales · 5 min read
How to Calculate a Tip
A percent of the bill, added on top — not a tax
A tip (gratuity) is a percentage of the bill added for service. This tutorial walks through tip = bill × rate and total = bill + tip, using the same $50 at 18% defaults as the Tip Calculator. Customary rates vary; the arithmetic does not decide who you tip or whether tax is in the base.
Written by the My Calculator Stack editorial team. About our methods
A tip percentage is a convention, not a legal tax rate. This page does not tell you whether to tip on pre-tax subtotal, post-tax total, or at all.
1.What a tip is
A tip is an amount added to a bill, usually expressed as a percent of the amount you choose as the base. It is not sales tax: tax is set by a jurisdiction; a tip is a gratuity. Some people apply the percent to the pre-tax subtotal; others use the total on the receipt. The calculator — and this widget — apply the rate to whatever bill figure you enter.
2.The formula
Tip T equals bill B times the tip rate t/100. The amount you pay is bill plus tip. An 18% tip is 0.18 times the bill, not 18 added as dollars. Split checks by dividing the total (or the tip) by the number of people after this step; this tutorial does not split the bill.
\[ T = B \times \frac{t}{100},\quad \mathrm{Total}=B+T \]
3.Worked example
The Tip Calculator defaults to a $50 bill at 18%. Tip = 50 × 0.18 = $9. Total = 50 + 9 = $59. At 15% the tip would be $7.50 and the total $57.50; at 20%, $10 and $60. Those are the same identity with a different rate — not a different formula.
\[ T=50\times 0.18=9,\quad \mathrm{Total}=59 \]
4.Bill stack playground
Move the tip-percent slider (and the bill if you want) to see the stack fill: subtotal, tip, and total. The caption substitutes your numbers into T = B × t/100. This is a teaching widget — no favorites, no full calculator chrome. Open the Tip Calculator when you want the standalone tool.
Inline playground
Tip / total
9.00 tip · 59.00 total
50 × 0.18 = 9; total = 50 + 9 = 59
Teaching aid only — the rate applies to the bill you enter. Customary rates and whether to include tax are your choice, not this identity.
Open the full Tip calculator →5.Open the full calculator
The Tip Calculator uses the same equation, the same $50 / 18% example, and How it works plus FAQ on one page. Enter a pre-tax subtotal there if that is your convention.
Try it yourself
Open the related calculator and put these formulas to work.