Box Offset Bend: The 10° Mini Offset

A box offset is a tiny, two-bend offset — usually just two 10° bends — that kicks the conduit sideways by the depth of a box knockout or surface-mounted raceway so the run sits flush. It is the most common bend nobody practices, and the easiest one to overthink.

The geometry in one line

A box offset is a standard offset with a 10° angle, so the 10° multiplier (6.0) applies: mark spacing = offset depth × 6. For a typical 1/2"-deep seating, the marks land about 3" apart. Shrink at 10° is about 1/16" per inch of offset — small enough to ignore on a short stub, but real on long runs.

How to bend one

1. Measure how deep the conduit must step — the knockout depth, say 1/2".
2. Compute spacing: 1/2" × 6 = 3" between marks.
3. Make the first mark near the conduit end (a couple of inches in gives the bender room to grip), the second mark 3" farther along.
4. Arrow on the first mark, bend to 10°. Flip the conduit, arrow on the second mark, bend 10° the opposite way.
5. Sight down the conduit: both straight sections should be parallel, in the same plane, with no twist — a twisted box offset will not sit flat against the box.

Why 10°?

Ten degrees is the sweet spot: shallow enough that the offset is compact and the conduit still pulls wire easily, steep enough that the marks stay a workable distance apart. Steeper angles make the box offset taller and harder to keep planar; shallower angles push the marks so far apart the "mini" offset stops being mini.

Field tips

• Bend both bends in the same plane. Roll the conduit between bends and you get a dogleg that rocks against the box — the classic box-offset failure.
• Check with a level before you cut: lay the offset against a flat surface and confirm both straight sections touch.
• Bend slightly past 10° and let springback settle it; checking the degree scale beats guessing.
• On long conduit, subtract the shrink (about 1/16" per inch of offset depth) from your measured run before marking.

What the app does for you

The offset calculator in Conduit Bend Calc runs this same math — enter the depth and 10°, and it returns the mark spacing and shrink so you can skip the mental arithmetic. Box offsets, full-size offsets, and kicks all use the same engine.