The work triangle
The sink, the cooktop and the fridge are the three work centres. The lines between their fronts form the work triangle.
The guidelines ask for each leg to measure between 1,22 and 2,74 m, and for the three together to add up to 7,92 m or less. A one-wall kitchen stretches the triangle along the wall, so its longest leg often runs long.
Source: NKBA, Kitchen Planning Guidelines with Access Standards
Counter beside each item
Keep free counter beside the sink (61 cm on one side, 46 cm on the other, and a 91 cm preparation area on one side), the cooktop (38 and 30 cm) and the fridge (38 cm on the handle side).
A dishwasher sits under the counter, so its top still counts; a fridge, an oven tower or a pantry does not. Around an inside corner the counter continues onto the next wall.
Source: NKBA, Kitchen Planning Guidelines with Access Standards