Do this by measuring from the left to the right side of the door.
Barn door measurements.
If the doorway has moldings measure from outside edge to outside edge to determine the proper door width add about 4 to 6 inches to your measurement.
Measure from outside to outside of casing molding.
How to measure for a barn door in three steps.
Measure the door width.
Exterior door sizes may even be larger.
Total door width will be 36.
Most barn door sizes fall anywhere between 36 wide on the shorter side by 96 tall on the longer side.
Your door s width should be 2 to 3 inches wider than the door opening and 1 inch higher than the dimensions of your opening.
Sheetrocked opening no trim or casing width.
Add 4 to the measurement and you have your recommended door width.
Barn door measuring guide for door openings with casing molding.
Generally most standard barn doors are approximately 36 x 84 or 42 x 80 with enough extra lip to overlap most standard door frames 36 x 80 by an inch or so.
In this example the opening width is 32 4.
Add 1 to 2 per door for overlap depending on privacy needs.
The average door width ranges from 24 inches to 36 inches.
Measure from inside to inside of the opening.
Using a tape measure begin at the left edge of the opening and measure straight across to the right edge.