Pergola Materials Calculator

Pergola material calculations:

Posts = 4 (for rectangular) or more for larger spans

Beams = 2 (run the length, sit on posts)

Rafters = (Length / Rafter Spacing) + 1 (run across the width, sit on beams)

Slats = (Width / Slat Spacing) + 1 (run the length, sit on rafters)

Standard sizing:

• Posts: 6×6 or 4×4 (15×15 cm or 10×10 cm)
• Beams: 2×8 or 2×10 (doubled for strength)
• Rafters: 2×6 or 2×8, spaced 16–24 inches (40–60 cm)
• Slats: 2×2 or 1×2, spaced 3–6 inches (8–15 cm)

Maximum spans without extra support:

• 4×4 posts: up to 8 ft (2.4 m) between
• 2×8 beams: up to 10 ft (3 m) span
• 2×6 rafters: up to 8 ft (2.4 m) span