Which unit was used by ancient Egyptians while building pyramids?

The cubit was the measurement unit used by Egyptians to  build the pyramid. The cubit is the measure from your elbow to the tip of your middle finger when your arm is extended.

For the construction of the puyramidcs, particularly the Great Pyramid of Giza, the royal cubitis thought to have been used, which is about 52.4 centimeters (20.6inches) long.