Tree Ring Block Math: How Many Curved Blocks for a Circle?

16" scalloped blocks. Need formula for circle diameter vs. block count.

No Magic Formula—Just Geometry

Circumference = π × diameter. Block length (chord) ≈ 16". But blocks are curved—inside face shorter.

Field Reality

• 3 blocks ≈ 20" ID circle (too small for a tree).
• 4 blocks = awkward gap.
• Minimum tree ring: 36" ID (trunk flare + mulch).
• That's ~7–8 blocks.

Better Options

• Poured concrete curb (machine or hand).
• Pre-cast metal tree rings (adjustable).
• Flexible plastic edging (bends to any radius).

Blocks don't stop roots. Tree outgrows the ring. Plan for maturity.