In most of the US, servers are legally paid a lower minimum wage on the assumption that tips make up the difference. A tip is not optional in practice, even though it is not written on the bill.
20% of the pre-tax bill is the common standard for sit-down restaurants with table service. 15% is considered the low end for adequate service; 25% is common for excellent service.
Card terminals almost always prompt for a tip percentage or amount before you can complete payment. Tipping is not expected at counter-service or fast-food restaurants, only where a server takes your order and brings food to the table.
Open the calculator with 20% pre-set →