Service is included in prices by law in the Netherlands, similar to several other Western European countries.
Rounding up the bill is common and appreciated. Around 5-10% is a generous amount for good service at a sit-down restaurant.
Card payment is the norm in the Netherlands, and terminals do not usually include a tip prompt, so rounding up in cash or telling the server the total you'd like to pay works best.
Open the calculator with 5% pre-set →