A complete guide — with formulas and examples — to calculating a tip, splitting a bill per person, uneven splits, and the pre-tax vs. post-tax question.
A tip (or gratuity) is a voluntary payment added to a bill to thank a server, bartender, delivery driver, or other service worker for their work. In the United States, tipping is deeply embedded in service-industry culture — many servers are legally paid a lower base wage precisely because tips are expected to make up the rest — which makes it more of a strong social expectation than the fully optional practice it is in many other countries. This calculator adds a tip to your bill, splits the total evenly or proportionally among a group, and can also work backward from a target payment to tell you what tip rate you'd need.
How is a tip amount calculated?
Quick answerTip = Subtotal × Percentage ÷ 100, where Subtotal is the bill amount before sales tax. For example, a $60 subtotal with a 20% tip is $60 × 20 ÷ 100 = $12, giving a grand total of $72.
- 15% tip: take 10% of the subtotal, then add half of that again (5%). $60 → $6 + $3 = $9.00.
- 18% tip: take 20% and subtract about 2% of the subtotal. $60 → $12 − $1.20 = $10.80.
- 20% tip: take 10% of the subtotal and double it. $60 → $6 × 2 = $12.00.
- 25% tip: divide the subtotal by 4. $60 → $60 ÷ 4 = $15.00.
How much does each person owe? (bill splitting)
Quick answerPer person = (Subtotal + Tip) ÷ Number of people. Add the tip to the subtotal to get the grand total, then divide by the group size. A $60 bill + 20% tip ($12) = $72 total; split 3 ways that's $24.00 each.
To avoid fumbling with change, you can round the grand total or the per-person amount up or down to a friendlier number. When you turn on rounding, this tool folds the small resulting difference back into the tip, so the amount you actually collect still matches the grand total exactly — nobody pays a penny more or less than intended.
How do you do an uneven split?
Quick answerUse Uneven Split mode and enter each person's own order total; the tool distributes the tip in proportion to those amounts. Someone who ordered a $30 steak pays a bigger share of the tip than someone who had a $10 salad, and every person's exact payment is shown separately.
Is the tip calculated before or after tax?
Quick answerThe US convention is to tip on the subtotal before sales tax, not on the tax-included total. Sales tax doesn't reflect service quality, so basing the tip only on the pre-tax amount is both standard etiquette and slightly cheaper for you. Just enter the pre-tax subtotal directly (the default assumption); if you only know the tax-included total, turn on "Bill amount includes sales tax" in Advanced settings and enter your local tax rate so it can be backed out first.
What about auto-gratuity for large parties?
Quick answerSome restaurants automatically add an 18–20% service charge to the bill for large parties (commonly 6 or more people). If your receipt already shows one, an additional tip is optional. Enter that existing charge into the "Included service charge / auto-gratuity" field under Advanced settings so the calculator accounts for it before adding anything further.