As a former waiter, I can say that if you think the service was good, 20% is the right percentage regardless of total bill. Traditionally, 15% is a normal tip for normal service (again, regardless of total bill). If you had a meal that cost $500, odds are that the waiter had to do a lot of work to get drinks, run food, deal with the chefs, etc. Remember that in almost all cases the waiters make 90% of their money from tips. Their hourly wages are way below minimum wage (when I was waiting tables a few years ago, my wage was less than $1.50 an hour). So when you stiff a waiter, you are really docking his or her pay.