Measure the length and width of the area in feet
Multiply length × width to get square feet
Choose the mulch depth in inches
Convert depth to feet by dividing inches by 12
Multiply square feet × depth in feet to get cubic feet
Divide cubic feet by 27 to get cubic yards
Use this shortcut: square feet × depth in inches ÷ 324 = cubic yards
Round up to the nearest bag or partial yard
Check the mulch bag coverage listed on the package
Divide total square feet by bag coverage to estimate number of bags