The Auditor
Enter your receipt numbers. We compute what the tip should be on both the pre-tax subtotal and the post-tax total, then compare against what the receipt printed.
Enter values and press "Audit the math".
Quick Tip Calculator
Bill Splitter
Splits the Quick Calculator's grand total evenly. Adjustment shifts each visible card; the first person absorbs the remainder.
Why receipts inflate the suggested tip
Most point-of-sale systems compute suggested gratuity on the post-tax total, not the pre-tax subtotal. At an 8.9% tax rate, a "20%" suggestion is really about 21.8% of your food and drink. On a $204.01 subtotal that is $44.43 instead of $40.80 — an extra $3.63 per dinner. Dine out weekly and that quiet rounding costs roughly $3.63 × 52 = $188.76 a year.
FAQ
Should tip be on pre-tax or post-tax?
Etiquette guides and the traditional convention say tip on the pre-tax subtotal — you tip on service, not on the government's cut. Tipping post-tax is a slightly more generous choice, but the receipt should not make it for you without saying so.
Why does the printed tip not match either calculation?
Sometimes the system includes discounted or comped items at full price, applies tip after mandatory service charges, or simply has a configuration error. That is the "Math error" verdict — worth a polite word with the manager.
Is a 40.802 result wrong?
No — 204.01 × 0.20 = 40.802, which rounds to $40.80. Fractions of a cent always round to the nearest cent on a bill.