How do I calculate a fair tip without arguing at the table?
Splitting dinner should be celebratory, yet somehow it ends with four adults squinting at a thermal receipt trying to remember 7th grade math.
The short answer
Find 10% of the pre-tax total by shifting the decimal one spot left, then double it for 20% or add half of it for 15%.
Step 1: Find the 10% baseline
Move the decimal point one place to the left. On an $86.40 bill, 10% is $8.64.
Step 2: Scale to your desired percentage
For 20%, double $8.64 to get $17.28. For 15%, take $8.64 and add half ($4.32) to get $12.96. For 18%, start from the 20% figure and subtract a fifth of the baseline: $17.28 minus $1.73 is $15.55.
Step 3: Split per person
Take the total (bill + tip) and divide by the number of paying adults. Use the round up button to avoid collecting loose change.
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Common mistakes
- Tipping on top of already included automatic gratuity. Check the receipt for a service charge first.
- Tipping on sales tax instead of the subtotal (though the difference is usually only a few quarters).
- Arguing over a $1.50 difference with close friends on a Friday night.