How To Calculate The Tip In Under 30 Seconds

Let's face it: It's a little embarrassing to pull out your phone at the restaurant for some sixth grade math.

America's tipping system is far from perfect, but the fact is, if you eat out and someone serves you, you need to tip them - unless the restaurant has adopted some sort of alternate policy. According to this chart from Wait But Why, you should never tip under 15%, and most diners tip anywhere from 17-20%.

How much is that, exactly? The calculator on your smartphone isn't the only quick way to calculate a tip. These shortcuts will give you the same result, and maybe a little boost in confidence.

We're not saying you need these strategies, but you can go ahead and bookmark this page "for a friend."

1. Move the decimal, then double the number.

You'll tip: 18%-20%

If you're looking for the easiest way to give 20%, this is it. Let's say your pretax bill is $53.75 (we'll use $53.75 in each of our examples for the sake of consistency).

1. Move the decimal point in your pretax bill one place to the left to get $5.375 from $53.75.
2. Round up to the next easy number: $5.40.
3. Double that number to get $10.80, which is 20% of your original bill.

In order to get as close to 20% as possible, but not go over, use standard rounding rules (if the number after the decimal on your total bill is 5 or higher, round up, if the number is lower than 5, round down).

If you prefer not to tip an entire 20%, you can modify step number two above to disregard the cents, and just double $5 to get a $10 tip - about 18%.

2. Double the number before moving the decimal.

You'll tip: 20%

The general idea is the same as the first method, but you double the number first, then move the decimal.

1. Round $53.75 up to $54.
2. Double that to get $108.
3. Move the decimal one place to the left and arrive again at $10.80, 20% of your original bill.

Follow the same rounding rules as explained in the first method.

3. Double the tax.

You'll tip: 15%-19%

1. Round up the tax to the nearest dollar. If your bill is $53.75 and the tax on the whole meal is $4.77, round up to $5.
2. Double the tax to get $10, which is about a 19% tip.

If you're splitting the meal with someone and they're also contributing to the tip, double the tax on only your portion of the bill. If you're the only one tipping, double the tax on the whole bill.

Note that because the tax imposed on restaurant meals varies across the country (the example here is the roughly 8% tax used in New York City), you'll end up with varying results depending on where you are. If you're worried that doubling the tax might mean you under-tip, better to go with another method.