How to Calculate Tips Quickly (Mental Math)

The check arrives and you need a tip amount in seconds. You shouldn’t need a calculator for this. With three simple mental math tricks, you can figure out 15%, 18%, or 20% of any bill in your head, every time.

This guide breaks down those shortcuts, covers tipping etiquette for every service type, and explains the fairest way to split a group bill. For exact numbers, our Tip Calculator does the math instantly.

The 10% Foundation

Every tip shortcut starts with 10%, which is the easiest percentage to calculate. Just move the decimal point one place to the left.

$47.80 bill: 10% = $4.78
$123.50 bill: 10% = $12.35
$8.60 bill: 10% = $0.86

Once you have 10%, you can build any common tip percentage from it.

Mental Math Shortcut: 15% Tip

Method: Find 10%, then add half of that amount.

Formula: 15% = 10% + 5% (which is half of 10%)

Example: Your lunch bill is $36.00.

10% of $36 = $3.60
Half of $3.60 = $1.80
Add them: $3.60 + $1.80 = $5.40 tip

With rounding: Round $36 to $40 for easier math. 10% of $40 = $4. Half = $2. Total = $6. You tip $6 instead of $5.40 and your server gets an extra sixty cents for your convenience.

Mental Math Shortcut: 18% Tip

Method: Find 20% and subtract a small amount, or find 10% + 10% - 2%.

Simpler approach: Find 20% (see below) and take a little off. On a $50 bill, 20% is $10. Knock off about $1 and leave $9. That is 18%.

Precise method for $72 bill:

10% = $7.20
8% = 10% minus 2% = $7.20 - $1.44 = $5.76
18% = 10% + 8% = $7.20 + $5.76 = $12.96, round to $13.

Most people simply split the difference between 15% and 20% and call it close enough. On a $72 bill, 15% is $10.80 and 20% is $14.40, so $12-$13 lands you at roughly 18%.

Mental Math Shortcut: 20% Tip

Method: Find 10% and double it.

Formula: 20% = 10% x 2

Example: Your dinner bill is $85.00.

10% of $85 = $8.50
Double it: $8.50 x 2 = $17.00 tip

This is the fastest tip to calculate mentally. Two steps, no fractions, no confusion. Many diners default to 20% specifically because the math is so simple.

Example 2: Bill is $53.47.

Round to $53. 10% = $5.30.
Double: $5.30 x 2 = $10.60.
Round up to $11 for a clean number.

Should You Tip on Tax?

Technically, tipping etiquette says you should tip on the pre-tax subtotal, not the after-tax total. Sales tax is money going to the government, not a charge for the service you received.

Example: Subtotal is $80. Tax (8%) adds $6.40. Total is $86.40.

Tip on subtotal: 20% of $80 = $16.00
Tip on total: 20% of $86.40 = $17.28

The difference is $1.28. In practice, most people tip on the total because it’s the bigger, bolder number on the receipt. Neither approach is wrong. Servers won’t complain about an extra dollar.

Pro tip: If the tax rate is high (9-10%+), tipping on the subtotal saves you a few dollars on expensive meals. On a $200 dinner with 10% tax, the difference is $4.

Tipping Guide by Service Type

Restaurants

Situation	Recommended Tip
Sit-down, good service	18-20%
Sit-down, excellent service	20-25%
Sit-down, poor service	10-15% (speak to manager)
Buffet	10%
Counter service / fast casual	$1-2 or 10%
Takeout	0-10% (optional but appreciated)
Catering / private chef	15-20% of total bill

Delivery Services

Service	Recommended Tip
Food delivery (app-based)	$3-5 minimum, or 15-20%
Pizza delivery	$3-5 minimum, or 15%
Grocery delivery	$5-10, or 15-20%
Furniture/appliance delivery	$10-20 per person

Note on delivery: The delivery fee charged by apps does not go to the driver in most cases. Your tip is often the driver’s primary compensation.

Personal Services

Service	Recommended Tip
Haircut	15-20%
Hair coloring / styling	20%
Massage	15-20%
Manicure / pedicure	20%
Tattoo	20-25%
Valet parking	$3-5
Hotel housekeeping	$3-5 per night
Hotel concierge (special request)	$5-20
Movers	$20-50 per mover

When Tipping Is Not Expected

Retail store employees (they typically can’t accept tips)
Doctors, dentists, lawyers, accountants (professional fee covers service)
Business owners who set their own prices (though exceptions exist for solo operators at salons)
Government employees (postal carriers in the US may accept gifts under $20 during holidays, but not cash)

How to Split a Bill Fairly

Even Split

The simplest approach: divide the total (including tip) by the number of people.

Example: Four friends. Bill is $148. Tip at 20% = $29.60. Total = $177.60.

Per person: $177.60 / 4 = $44.40 each

Proportional Split

Fair when orders vary widely. Each person pays based on what they ordered.

Example: Three diners. Alice ordered $45, Bob ordered $28, Carol ordered $35. Subtotal = $108.

Alice’s share: $45 / $108 = 41.7%
Bob’s share: $28 / $108 = 25.9%
Carol’s share: $35 / $108 = 32.4%

Add a 20% tip ($21.60), total = $129.60.

Alice pays: $129.60 x 0.417 = $54.04
Bob pays: $129.60 x 0.259 = $33.57
Carol pays: $129.60 x 0.324 = $41.99

Our Tip Calculator handles this split automatically. Enter the bill, choose a tip percentage, set the number of people, and get each person’s share.

The Shared Appetizer Problem

When the table orders shared plates, split those items evenly among everyone who ate them, then add each person’s individual items.

International Tipping Customs

Tipping norms vary dramatically by country. What is generous in the US may be confusing or even offensive elsewhere.

Country	Custom
United States	15-25%, expected
Canada	15-20%, expected
United Kingdom	10-15% at restaurants, check for service charge
France	Service included (“service compris”), round up 1-2 euros
Germany	Round up to nearest euro or add 5-10%
Italy	”Coperto” (cover charge) included, tip 1-2 euros extra
Japan	No tipping. It can be considered rude
South Korea	No tipping expected
Australia	Not expected, but 10% appreciated for great service
Mexico	10-15% at restaurants
Brazil	10% service charge usually included (“10% servico”)

Rule of thumb when traveling: Research tipping customs before your trip. When uncertain, ask hotel staff or check the bill for an included service charge.

Quick Mental Math Reference Card

Bill Amount	15% Tip	18% Tip	20% Tip
$20	$3.00	$3.60	$4.00
$30	$4.50	$5.40	$6.00
$40	$6.00	$7.20	$8.00
$50	$7.50	$9.00	$10.00
$60	$9.00	$10.80	$12.00
$80	$12.00	$14.40	$16.00
$100	$15.00	$18.00	$20.00
$150	$22.50	$27.00	$30.00
$200	$30.00	$36.00	$40.00

Skip the Guesswork

Our Tip Calculator lets you enter any bill amount, choose your tip percentage, and split across any number of people instantly. Use the Percentage Calculator for custom tip rates beyond the standard options.

Frequently Asked Questions

Should I tip on alcohol?

Yes. Tip on the full bill including drinks. Bartenders and servers handle your drink orders just like food orders, and alcohol is often where restaurants earn higher margins that support staff wages. The only exception is if you received a separate bar tab with its own gratuity.

What if the service was terrible?

Leaving zero tip sends a message, but 10% is a more measured response that still communicates dissatisfaction. Speak to the manager about specific problems. Keep in mind that kitchen delays, food quality issues, and long waits during a rush are usually not the server’s fault. Tip the server for their attentiveness, not the kitchen’s speed.

Is it rude to use a tip calculator at the table?

Not at all. Using a tool to calculate an accurate tip shows you care about getting it right. It is far better than guessing low. Most people check their phones at restaurants anyway. Our Tip Calculator is designed to give you a fast, accurate answer without any awkwardness.

Do I need to tip for counter service or coffee shops?

Counter service tips are optional but increasingly expected, especially at coffee shops and fast-casual restaurants. A dollar or two per order, or 10-15%, is appropriate if you feel the service warrants it. The tip jar or screen prompt is a suggestion, not an obligation.