Compound 90 calculator (two-bend 90)

Sometimes a single 90 would hit something in the corner — a beam flange, a round duct, another run. Splitting the turn into two bends that add up to 90 (30 + 60, 45 + 45, 60 + 30) lets the conduit cut the corner and clear it. The math is the offset multiplier again.

Last reviewed Nov 14, 2026 · Sources at the end of the page

The formula

Second bend = 90° − first bend
Clear depth = protrusion + clearance (corner) or radius + ½ OD + clearance (round)
Diagonal between bends = clear depth × multiplier of the first bend

The diagonal works exactly like the distance between bends in an offset: the clear depth is the "offset" and the first bend's multiplier (1 ÷ sin θ, published as 2.0 at 30° and 1.4 at 45° by Greenlee, Klein and Gardner Bender) scales it.

Worked example: 6″ corner, ½″ clearance, 45° + 45°

1. Clear depth: 6 + ½ = 6 1/2″.
2. Second bend: 90 − 45 = 45°.
3. Diagonal: 6½ × 1.414 = 9 3/16″ between the bends.

Which split to use

• 45° + 45° — symmetrical, the most common choice.
• 30° + 60° — the first bend leaves the floor gently; good when the obstruction is near the floor end.
• 60° + 30° — climbs fast, then eases into the wall.

Keep both bends in one plane, and sight down the run before you strap it. For a large smooth radius instead of two bends, see the segmented 90.