Choose a place in the room that will be your starting point for measuring the baseboards. Typically, it is easiest to start with the first wall to the left of the main door in the room.
Draw a rough outline of the room on a piece of paper with a pencil. Indicate where the doors in the room are located.
Measure the first length of baseboard with a measuring tape. Ask a partner to hold the measuring tape flat against the wall above the baseboard while you stretch the tape out to the end of the baseboard. Take the measurement to the closest 1/16th of an inch. Write the measurement down on a piece of paper, matching the measurement with the appropriate wall in the rough outline.
Measure the remaining baseboards with the measuring tape. Write the measurements down with the corresponding walls on the rough outline of the room. When you are finished, you should have a rough drawing of the room with the measurements of the baseboards next to the walls.