Before tax
$100.00 × 20% = $20.00.
Free suggested-tip checker
Was the suggested tip based on tax?
Reviewed for math and source accuracy August 12, 2026.
Enter the subtotal, tax, printed percentage, and suggested tip amount. The checker compares the suggestion with the same percentage before tax and after tax.
Compare both bases
See the tip math side by side.
Use the numbers printed on the receipt. The result shows which calculation is closer without choosing a tip for you.
Worked example
A 20% suggestion can mean two different amounts.
For a $100.00 subtotal with $8.25 tax, 20% before tax is $20.00. Twenty percent of $108.25 after tax is $21.65.
After tax
$108.25 × 20% = $21.65.
Difference
The after-tax calculation is $1.65 higher in this example.
What the comparison tells you
What the comparison means.
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Before-tax amount
The entered percentage is applied to the printed subtotal only.
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After-tax amount
The same percentage is applied to the subtotal plus the printed tax.
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Closest calculation
The checker compares the printed suggestion with both rounded dollar amounts.
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Your next move
Review the receipt and choose what, if anything, you want to enter as the tip.
Math method
How the comparison is calculated.
The printed percentage is applied once to the subtotal and once to the subtotal plus tax. Each result is rounded to the nearest cent, then compared with the printed suggested-tip amount. The checker does not choose a tip or calculation base.
Suggested-tip checker questions.
Does this tell me how much I should tip?
No. It compares the printed suggestion with two arithmetic bases. The percentage and final amount remain your choice.
What if the suggestion matches neither amount?
The receipt may use different rounding, include another charge in its base, or contain a printed amount that does not match the stated percentage. The checker shows the two calculations so you can compare them.
Should a service charge be included in the subtotal?
For this comparison, use the subtotal printed before tax and separately listed fees. Review the service charge separately because receipt layouts and restaurant policies vary.
Ready for the next bill?
Check the math before you split it.
Fetti Up can point out a tip that appears to use the amount after tax. You review the receipt and decide what to change.