Truss Spacing Calculator
Truss spacing — the on-center distance between trusses — is usually 24", 19.2", 16", or 12", and it directly controls how many trusses a roof needs and how much load each one carries. This calculator shows truss count and board footage for your chosen spacing.
Calculate Your Truss Spacing
Enter your building specifications below. Results and the roof diagram update live as you type.
Live Roof Diagram
Results
Estimate Your Project Budget
Automatically calculated from your inputs above in the calculator.
Estimates only. Actual costs vary by region, supplier, and site conditions.
Choosing the Right Truss Spacing
24" on-center is the standard residential default because it uses the fewest trusses per foot of building length while still matching common roof sheathing panel dimensions (4x8 sheets divide evenly into 24" spacing).
Closer spacing — 16" or 12" on-center — is used when roof loads are heavier (high snow load regions), when sheathing spans need to be shorter, or when truss chord sizes are being kept smaller intentionally. Closer spacing means more trusses, more connector plates, and more labor, but each truss carries less load.
19.2" on-center is a common middle-ground spacing (dividing an 8 ft sheet into five equal panels) used to balance material efficiency against load distribution. Switch the spacing dropdown in the calculator above to compare truss count and cost across all four standard spacings for your span.
Frequently Asked Questions
What is standard truss spacing?
24 inches on-center is the standard residential truss spacing in North America, chosen because it divides evenly into standard 4x8 ft sheathing panels while minimizing truss count.
Does closer truss spacing mean stronger roof?
Closer spacing distributes roof load across more trusses, so each individual truss carries less load — useful for heavy snow regions — but it does not increase the strength of any single truss; that is set by chord size and web design.