How to Calculate a Tip (and Split the Bill)
A tip is the bill times a percentage, and the quickest way to get there is to find 10% by moving the decimal point one place left, then double it or add half. Below: the customary US rates, the mental-math method with worked examples, the pre-tax question, and how to split a bill fairly. A tip calculator takes the bill, the percentage and the number of people and returns each person's share including the tip.
Standard Tipping Percentages
For sit-down restaurant service in the United States, the Emily Post Institute's guideline is 15–20% of the pre-tax bill. Three numbers cover most situations:
- 15% for adequate service.
- 18% for good, attentive service; it is also the tip calculator's default.
- 20% for very good service.
The Quick Mental-Math Method
Start from 10%, which only takes moving the decimal point one place to the left:
- 10% of $48 = $4.80
- 10% of $72.50 = $7.25
- 10% of $130 = $13.00
- 20%: double the 10% figure ($4.80 becomes $9.60).
- 15%: take 10%, then add half of it ($4.80 + $2.40 = $7.20).
- 18%: find 20% and take a little off, or take 15% and add a little (18% of $48 is $8.64).
Worked Examples
A casual lunch. The bill is $36. Ten percent is $3.60; double it for 20% = $7.20. Round up to $7.50 and the total is $43.50.
Dinner for two. The check is $94.80. Ten percent is $9.48, so 20% is $18.96 and 18% is $17.06. Leaving $17 brings the total to $111.80; leaving $18.20 makes an even $113.
A bigger tab. A celebratory meal costs $215. Ten percent is $21.50; doubling gives $43.00 for a 20% tip and a $258.00 total. For 15%, add half of $21.50 ($10.75) to get $32.25.
Every calculation starts by sliding the decimal one place left; the rest is doubling, halving and rounding.
Pre-Tax vs Post-Tax Totals
Tips reward service, and tax goes to the government, so the pre-tax subtotal is the conventional base; Emily Post's guideline says pre-tax explicitly. The difference is small: on a $100 meal with 8% sales tax, 20% is $20.00 pre-tax and $21.60 post-tax. Many people tip on the post-tax total because it is the number printed at the bottom of the receipt.
Check large-party receipts for an automatic gratuity (often 18–20%) before adding a tip, so you don't tip twice.
Splitting a Bill Evenly
Add the tip first, then divide. Four friends share a $120 dinner: a 20% tip ($24) makes $144, and $144 ÷ 4 = $36 each. Rounding each share up to $37 gives a small cushion so the pooled cash covers the bill. The tip calculator does this directly: enter $120, 20% and 4 people and it returns $36.00 per person.
Splitting a Bill Unevenly
When one person had the steak and another a salad, split in proportion to what each ordered:
1. Note each person's subtotal.
2. Apply the same tip percentage to each subtotal.
3. Add tax in the same proportion if you are including it.
If Alex ordered $40 and Jordan $20 of a $60 bill, a 20% tip ($12) splits $8 to Alex and $4 to Jordan. When the amounts are close, an even split is faster; save the proportional math for a large gap.
Customary Rates for Other Services
The Emily Post Institute's general tipping guide gives these customary US amounts:
- Sit-down restaurants: 15–20% of the pre-tax bill.
- Bartenders: $1–2 per drink, or 15–20% of the tab.
- Food delivery: 10–15% of the bill; $2–5 for pizza delivery depending on the order and the trip.
- Taxi drivers: 15–20% of the fare, at least $1, plus $1–2 per bag the driver handles.
- Hair salons: 15–20%, split among the people who served you.
- Hotel housekeeping: $2–5 per day, left daily with a note.