How to Measure Staircase Spindles, Risers, and Treads for Enamel

Staircases have high surface area due to 4-sided balusters. Rules of thumb: 1) Balusters/Spindles: Each standard 36-inch turned or square wood baluster equals approximately 1.0 to 1.2 sq ft of surface area (a 30-spindle staircase = 35 sq ft); 2) Stair Risers: Average riser (7 in × 36 in) = 1.75 sq ft each (14 risers = 25 sq ft); 3) Handrail & Skirtboards: Add 35 sq ft. For a standard 14-step staircase with balusters and risers, 1 gallon of bonding primer and 1 gallon of semi-gloss urethane enamel provides 2 full coats.

Beautifully painted white stair balusters spindles and dark stained oak treads in a two story foyer

Published 2026-03-01 · Updated 2026-03-01 · 8 min read

Component-by-Component Surface Area Formulas

• Square Baluster (1.5" × 1.5" × 36"): 4 sides × 0.125 ft × 3 ft = 1.5 sq ft per spindle.

• Stair Riser (7.5" × 42"): 0.625 ft × 3.5 ft = 2.18 sq ft per step.

• Stair Stringer / Skirt Board: Length × 0.8 ft = ~15 sq ft per side.

• Handrail (Perimeter profile): 0.5 ft circumference × 14 ft length = 7 sq ft.

Worked Example: 14-Step Staircase Refinishing (28 Spindles + 14 Risers + 2 Skirtboards)

Refinishing stair components with 1 coat bonding primer and 2 coats urethane enamel.

One gallon of urethane enamel easily covers all spindles, risers, and skirt boards for 2 complete coats.

What brush is best for painting intricate stair spindles?

A 1.5-inch or 2.0-inch angled sash brush with soft chinex or nylon-poly bristles provides maximum control without leaving heavy paint runs on curved spindle turnings.

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