How to Choose SUP Thickness — Engineering Analysis

The Three Standard Thicknesses

4" (10 cm) – Touring & Performance

• Highest rigidity – less flex under load
• Lightest – less material, less air volume
• Excellent tracking – reduced side-to-side rocking
• Fastest – reduced drag, easier glide
• Best for: Touring, racing, fitness paddling, experienced paddlers

5" (12.7 cm) – All-Around

• Good rigidity – balanced flex-to-stiffness ratio
• Moderate weight – standard material usage
• Good primary + secondary stability
• Best for: Recreational paddling, beginners, casual lake and river use

6" (15.2 cm) – Stability & Yoga

• Highest primary stability – massive buoyancy
• Heaviest – more PVC material, larger air volume
• Slowest – more drag, harder to maintain glide
• Best for: Yoga/fitness, heavy paddlers (100+ kg), very choppy conditions

Engineering Analysis

The stiffness of an inflatable SUP is governed by internal air pressure and the moment of inertia of the board's cross-section. At 20 PSI, a 4" board shows approximately 30% less deflection under load than a 6" board of the same width and length. Primary stability comes from waterline width and buoyancy; secondary stability is influenced by rail shape and board width.

Thickness by Paddler Weight

Paddler Weight	Recommended Thickness
Under 65 kg (143 lbs)	4"
65 – 90 kg (143 – 198 lbs)	5"
90 – 115 kg (198 – 253 lbs)	5" or 6"
Over 115 kg (253 lbs)	6"

Thickness vs. PSI Trade-off

A common misconception is that higher PSI can compensate for excessive thickness. At 25 PSI, a 6" board shows more flex than a 4" board at 15 PSI because the geometric moment of inertia dominates the stiffness equation. For performance-oriented paddlers, a thinner board at lower pressure outperforms a thicker board at higher pressure.

Afarer Lineup

• 4" boards: Cheetah Touring series – 12' x 30" x 4" touring SUPs for fitness and distance paddling
• 5" boards: Cheetah All-Round series – 10'6" x 32" x 5" for recreational use
• 6" boards: Cheetah Ultra-Stable series – 10' x 34" x 6" for yoga, large paddlers, and photography platforms

All boards utilize 1,680 DTEX drop-stitch cores with 15 PSI rated pressure and 1.2 mm PVC laminates.

Thickness, PSI, and fabric spec are all configurable for custom lines — see how we engineer boards for OEM and private-label brands and walk through our board construction at the factory floor.