Turn off the chainsaw and remove the spark plug wire or battery
Lay the chainsaw on a flat surface
Find the bar tip and the point where the bar enters the saw body
Measure from the tip of the bar to the point where it enters the saw body
Round the measurement to the nearest even inch
Use the measured length as the bar size
Check the bar stamp for the manufacturer’s listed length if needed
Measure the chain pitch and gauge separately if replacing the bar or chain