How to Calculate a Tip: Easy Tricks for 15%, 18%, and 20%

To calculate a tip, multiply your bill by the tip percentage. For a 20% tip, multiply by 0.20. For a 15% tip, multiply by 0.15.

But the fastest way is to do it in your head:

1. Find 10% by moving the decimal point one place to the left. For a $42.00 bill, 10% is $4.20.
2. For 20%, double it: $4.20 × 2 = $8.40.
3. For 15%, add half of the 10%: $4.20 + $2.10 = $6.30.

That is all you need for most bills. Below, you will find more easy tricks, a tip chart, and how to split the bill with friends. If you would rather let a tool do the math, try our free online percent calculator.

The basic tip formula

Tip = bill × (tip percent ÷ 100)

Total to pay = bill + tip

For example, for an 18% tip on a $50 bill:

• 18 ÷ 100 = 0.18
• $50 × 0.18 = $9.00 tip
• $50 + $9 = $59.00 total

You can also find the total in one step. Add 1 to the decimal and multiply:

• $50 × 1.18 = $59.00

Why the 10% trick works

Percent means "out of 100." So 10% means 10 out of 100, which is the same as one tenth. When you move the decimal point one place to the left, you are dividing by 10. That gives you one tenth, or 10%, of the number.

Once you know 10%, you can build almost any other tip from it:

• 20% is two groups of 10%
• 30% is three groups of 10%
• 5% is half of 10%
• 15% is 10% plus 5%

This is why finding 10% first is the key to doing tips in your head.

Easy tricks to calculate a tip in your head

How to calculate a 10% tip

Move the decimal point one place to the left.

• $36.00 → $3.60
• $87.50 → $8.75
• $124.00 → $12.40

How to calculate a 20% tip

Find 10%, then double it.

• $36.00 → 10% is $3.60 → 20% is $7.20
• $87.50 → 10% is $8.75 → 20% is $17.50

Another trick: Double the bill, then move the decimal point one place to the left. $36 × 2 = $72 → $7.20.

How to calculate a 15% tip

Find 10%, then add half of it.

• $40.00 → 10% is $4.00, half is $2.00 → 15% is $6.00
• $64.00 → 10% is $6.40, half is $3.20 → 15% is $9.60

How to calculate an 18% tip

Find 20%, then subtract 2%. (2% is 10% divided by 5.)

• $50.00 → 20% is $10.00, 2% is $1.00 → 18% is $9.00

Or, find 20% and round down a little. It gets you very close.

How to calculate a 25% tip

Divide the bill by 4.

• $60.00 ÷ 4 = $15.00

How to calculate a 5% tip

Find 10%, then cut it in half.

• $30.00 → 10% is $3.00 → 5% is $1.50

Tip chart

Use this chart for quick answers.

How to calculate a tip on a calculator

1. Type your bill amount.
2. Press × (times).
3. Type the tip as a decimal: 0.15 for 15%, 0.18 for 18%, or 0.20 for 20%.
4. Press =. That is your tip.
5. Add it to your bill for the total.

Or, to get the total in one step, multiply your bill by 1.15, 1.18, or 1.20.

How to split the bill and tip

When you eat out with friends, here are two easy ways to split the check.

Split evenly

1. Add the tip to the total bill.
2. Divide by the number of people.

Example: The bill is $120 for 4 people, and you want to leave 20%.

• Tip: $120 × 0.20 = $24
• Total: $120 + $24 = $144
• Each person pays: $144 ÷ 4 = $36

Split by what each person ordered

1. Each person adds up what they ordered.
2. Each person figures their own tip on that amount.
3. Share the tax fairly, or tip on the total before tax.

Example: You ordered $28 worth of food. A 20% tip on that is $5.60, so you put in $33.60, plus your part of the tax.

What about tip screens and suggested tips?

Many stores and restaurants now use a tablet or card reader that shows suggested tips, like 18%, 20%, and 25%. Here is how to handle them:

• Check what the percentage is based on. Some screens calculate the tip on the total after tax, which makes the suggested amounts a little higher.
• Use the "custom tip" button if you want to leave a different amount. You can type in any number you like.
• It is okay to choose "no tip" at a counter where you order and pick up your own food, although many people still leave a small amount.
• Look at the dollar amount, not just the percentage, before you tap.

Knowing the 10% trick makes it easy to check if a suggested tip looks right.

Should you tip before or after tax?

Many people calculate the tip on the amount before tax, because the tax is not part of the service. Others tip on the total, because it is easier and the difference is small.

For example, on a $50 bill with $4 of tax:

• 20% of $50 (before tax) = $10.00
• 20% of $54 (after tax) = $10.80

Both are common. Choose what feels right to you.

How much to tip in the United States

Tipping customs vary by place, type of service, and personal choice. These are common ranges in the U.S.:

Some restaurants add a service charge or automatic gratuity for large groups. Check your bill before you add a tip, so you do not tip twice.

Outside the U.S., tipping customs can be very different. In some countries, a service charge is already included, and tipping extra is not expected.

Tipping in different situations

Takeout and pickup orders

Tipping on takeout is up to you. Many people leave a small tip, often around 10%, or round up the bill, especially for big or complicated orders.

Buffets

At a buffet, you serve yourself, but staff still bring drinks and clear plates. A tip of around 10% is common.

When service was bad

If something went wrong, it is usually better to talk to a manager than to skip the tip. Many servers are paid a low hourly wage and depend on tips. If the problem was the kitchen, not the server, try not to take it out on the tip.

Large groups

For groups of 6 or more, many restaurants add an automatic gratuity, often 18% to 20%. Look for words like "gratuity" or "service charge" on your bill.

Gift cards and coupons

If you use a coupon or gift card, it is kind to tip on the full price before the discount. The server did the same amount of work.

Practice: calculate these tips

Try these in your head. The answers are below.

1. A 20% tip on a $35 bill
2. A 15% tip on a $60 bill
3. A 20% tip on a $82 bill
4. A 15% tip on a $24 bill
5. A 25% tip on a $48 bill

Answers:

1. 10% is $3.50, doubled is $7.00
2. 10% is $6.00, plus half ($3.00) is $9.00
3. 10% is $8.20, doubled is $16.40
4. 10% is $2.40, plus half ($1.20) is $3.60
5. $48 ÷ 4 is $12.00

Common tipping math mistakes

• Tipping twice. Check for an automatic gratuity or service charge on the receipt.
• Moving the decimal the wrong way. 10% of $45 is $4.50, not $450 or $0.45.
• Forgetting to add the tip to the total when splitting the bill.
• Using the wrong percentage. Double-check that you multiplied by 0.15, not 1.5.

Should you round up your tip?

Many people round their tip up to the nearest dollar to keep things simple. If a 20% tip comes out to $7.40, leaving $7.50 or $8.00 is easy and kind. Rounding the total is also popular. If your bill plus tip is $52.60, you might just pay $53.

Rounding up makes the math faster, saves you from carrying lots of coins, and servers appreciate it.

Tips are just percentages

Calculating a tip is the same as finding a percentage of a number. Once you know the tricks, you can use them for sales, discounts, and more. To learn how to figure out how much a price went up or down, read our guide on how to calculate percentage change.

The bottom line

To calculate a tip, start by finding 10% of your bill by moving the decimal point one place to the left. Double it for 20%, or add half of it for 15%. Round your bill to make the math easier, and check the receipt for any service charge before you tip. For quick, exact answers, let our calculator do the math.