Calculate the tip amount, total bill, and per-person share in seconds.
In the US, 15-20% is typical for sit-down restaurant service, with 20%+ common for excellent service. Tipping norms vary significantly by country, so adjust the percentage to fit local custom.
Either is acceptable; tipping on the pre-tax amount is slightly more common and is what most people mean by the bill total.
The total bill plus tip is divided evenly by the number of people entered.