Deck Railing Calculator
Calculate deck railing materials including posts, balusters, rails, and hardware for wood, composite, aluminum, cable, or glass railings.
How to Use This Calculator
Calculate deck railing materials with these steps:
- Enter the total linear feet of railing needed (all sides requiring railings)
- Select your railing height (36 inches residential minimum, 42 inches commercial)
- Choose your baluster/infill style (wood, aluminum, composite, cable, or glass)
- Specify post spacing (6 feet standard for wood, 4 feet for cable/glass)
- Add any stair run length if applicable
Why This Matters
Deck railings are a critical safety feature required by code for any deck surface more than 30 inches above grade. Improperly spaced balusters can trap children, while inadequate post anchoring can cause catastrophic failures.
- Calculate exact post and baluster quantities
- Ensure code-compliant spacing (4 inch max between balusters)
- Account for stair rail length (angled = longer)
- Estimate material costs for different styles
Worked Examples
12x16 Deck - Wood Railing
Railing on 3 sides, 36 inch height, 6 foot post spacing
Calculation: 44 feet total length, 9 posts, 44 × 3.43 balusters
Result: 9 posts, 48 ft rails (each), 151 balusters
Cable Railing with Stairs
40 feet perimeter + 8 foot stair run
Calculation: 40 + (8 × 1.4) = 51.2 feet total length
Result: Posts at 4 foot centers, 4 horizontal cable rows
Common Mistakes to Avoid
- Attaching posts only to decking instead of bolting to joists
- Spacing balusters more than 4 inches apart (code violation)
- Using under-height railings (36 inches minimum)
- Forgetting stair rails are angled and need more length
- Overlooking graspable handrail requirement for stairs