Two-thirds cup of butter is equal to 10 2/3 tablespoons. Most butter packages have measuring amounts marked on the sides of the paper wrapping to help you easily cut the amount you need. The standard 1/4-pound stick of butter is equal to 1/2 cup and 8 tablespoons.
The liquid displacement method of measuring is a good way to measure solid fats like butter. To use the liquid displacement method to measure 2/3 cup butter, fill a liquid measuring cup with 1 cup of cold water. Then, add the solid butter until the liquid reaches 1 2/3 cups. Pour out the water and use the butter.