How to calculate a tip

Calculating a tip is multiplying by 0.20. That was never the hard part. The hard parts are deciding which number to apply the percentage to, spotting when a gratuity has already been added without you noticing, and splitting the bill without anyone feeling squeezed. This guide covers those three decisions.

The arithmetic, quickly

tip = bill × (percentage ÷ 100)

The mental shortcut that always works: 10% is moving the decimal one place left. $138 → $13.80. From there, 15% is that plus half of it ($20.70) and 20% is double it ($27.60). No other calculation is needed.

Bill	15%	18%	20%
$50	$7.50	$9.00	$10.00
$80	$12.00	$14.40	$16.00
$120	$18.00	$21.60	$24.00
$200	$30.00	$36.00	$40.00

Tip on the pre-tax total, not the post-tax one

Sales tax is money the restaurant collects for the state. Your server did no additional work because the tax exists, so the customary base for the tip is the pre-tax subtotal.

How much does it matter? On a $100 check in a city with 8.875% sales tax, the total is $108.88. Tipping 20% on the pre-tax subtotal is $20.00; tipping 20% on the total is $21.78 — the same gesture now costs 21.8% of the subtotal. Small on one dinner, meaningful across a year.

Nobody will object either way. But if you are trying to hit a specific level of generosity, the subtotal is the number that defines it.

The most common trap: tipping twice

Many restaurants add an automatic gratuity for large parties — often 18% to 20% for six or more — and it appears on the check as "service charge", "gratuity" or "service". Adding another 20% on top of that means paying twice.

A $200 check with an 18% auto-gratuity comes to $236. Adding a further 20% on that total tacks on $47.20 and takes the payment to $283.20 — an effective tip of 41.6%, roughly double the intent.

Checking takes five seconds: scan the check for a line that is not food, drink or tax. If it is there, the tip is paid, and the tip line on the slip is optional extra.

Which number when there is a discount

You used a coupon for 40% off. The full check was $200 and you pay $120. Which figure does the tip apply to?

The honest answer is $200. The discount was the restaurant's commercial decision; the work of serving you was identical. Tipping on $120 passes the cost of a promotion your server did not choose onto your server — $24 instead of $40 at 20%.

The same reasoning covers comps: if the kitchen sent out a free dessert, someone still served that dessert.

Tip screens are not a rule

Payment tablets now ask for a tip in places that never had tipping — counter service, pickup orders, self-serve. The defaults are frequently 20%, 25% and 30%, and they are calculated on the post-tax total.

Those numbers are a merchant setting, not a social standard. The convention worth keeping is straightforward: full table service, tip 18% to 20%; counter service where someone handed you a coffee, a dollar or two or nothing is normal. Being prompted is not the same thing as being expected.

Splitting without friction

Most of the awkwardness in splitting a check is social, not mathematical. Three rules handle nearly all of it:

• Agree on the model before ordering, not when the check lands. "Are we splitting evenly?" costs five seconds up front and prevents the uncomfortable conversation at the end, when one person has had three cocktails and another had tap water.
• Split the total including the tip. Splitting the bill and letting everyone add their own tip reliably comes up short.
• Always round up. Two dollars extra is irrelevant; two dollars missing forces someone to cover it. On a $236 check split five ways, $47.20 each becomes $48 — and nobody is hunting for coins.

Frequently asked questions

Why is tipping so much higher in the US? Because it is structural, not etiquette. Federal law allows a tipped minimum wage well below the standard one where tips make up the difference, so in many states a server's income depends on tips rather than supplementing it. Not tipping is, in practice, not paying for the service.

Should I tip on delivery? Yes, and generally as a percentage with a floor — around 15% to 20%, but not less than $3 to $5 on a small order. Bad weather, long distances and walk-up buildings are exactly the cases where it matters most.

Cash or on the card? Either reaches the server, but cash usually arrives faster and in full. If you tip in cash on a card payment, say so, and write "cash" on the tip line so it is not entered twice.

What about services that are not restaurants? Common US conventions: 15% to 20% for hair and personal care; $2 to $5 per bag for hotel porters; $3 to $5 a night for housekeeping, left daily; 15% to 20% for taxis and rideshare. Movers, tattoo artists and food delivery generally follow the restaurant range.