How this is calculated
tip = bill × tip % ; each person = (bill + tip) ÷ people
The math is the easy part: tip equals the bill times the percentage, and the split divides the total evenly. The value of a tip calculator is social — it replaces the end-of-dinner mental arithmetic (and the person who 'forgot' the tip in their share) with one agreed number.
Tipping norms are wildly regional. In the US, 18-20% at sit-down restaurants is the standard, 15% reads as mild dissatisfaction, and counter service commonly suggests 10-15% on screens. Much of Europe includes service in the price, making 5-10% a generous rounding; Japan famously doesn't tip at all. When traveling, five seconds of local research saves both money and awkwardness.
One honest question people quietly ask: pre-tax or post-tax? Tradition says tip on the pre-tax amount; in practice most people tip on the total because that's the number on the bill. On a typical bill the difference is small change — pick one and stop re-litigating it at the table.
Frequently asked questions
How much should I tip in the US?
Sit-down restaurants: 18-20% is standard, more for exceptional service. Bars: $1-2 per drink or ~20% on a tab. Delivery: 15-20% with a sensible minimum. Counter-service screens are genuinely optional territory.
Tip on the pre-tax or post-tax amount?
Etiquette tradition says pre-tax; most people use the post-tax total for simplicity. On a $60 bill the difference is well under a dollar per person — either is defensible.
What if service was bad?
In the US, tipping down to ~10-15% signals dissatisfaction while acknowledging servers depend on tips for base income. Zero is reserved for genuinely hostile service — and telling a manager helps more than a stealth zero.