Offset Bend: Travel, Shrink and Bend Marks

Reviewed October 8, 2026

Open the offset bend calculator

Which distance are you calculating?

• Offset h: perpendicular separation of the parallel runs.
• Travel t: sloping length between ideal corners, t = h / sin θ.
• Run x: horizontal distance between those corners, x = h / tan θ.
• Ideal shrink s: loss of forward reach versus a straight segment of length t, s = t − x = h tan(θ/2).

Reproducible geometry example

For a teaching offset of h = 4 in and θ = 30°: t = 4 / 0.5 = 8 in; x = 4 / tan 30° ≈ 6.928 in; s = 8 − 6.928 ≈ 1.072 in. These are ideal geometric quantities. They do not include the curved portions of a real bend or the tool's marking conventions.

Manufacturer marking factors: a different calculation

Klein Tools Conduit Bender Guide, pages 6–7 gives these selected offset factors. Check the guide for the tool and conduit you actually use.

Original marking example following that convention: for a 4-in offset at 30°, with the obstacle reference 24 in from the conduit end, shrink compensation is 4 × 1/4 = 1 in. The first mark is 24 + 1 = 25 in from the end. Mark spacing is 4 × 2 = 8 in. Follow the manual's illustrated direction and bender-symbol alignment to place the second mark; do not substitute a center, star or arrow indiscriminately.

The 1-in field allowance differs from the 1.072-in ideal result because the two calculations use different models. Do not mix an exact multiplier with a rounded shrink table and call the combined result exact.

Developed length includes real bend arcs

Developed length is the length along the conduit centerline. For a known centerline layout, add every straight tangent segment and each arc: L = ΣL_straight + Σ(Rθ), with θ in radians and R the centerline radius. If angle is in degrees, use R × θ × π / 180. A pair of 30° arcs with an assumed 3-in centerline radius contributes 2 × 3 × π/6 = π ≈ 3.142 in of arc length.

That arc total is not a cut length. The tangent lengths must be derived from the same rounded geometry; simply adding it to the 8-in sharp-corner travel double-counts parts of the bend. Use the actual tool radius, reference marks, conduit size and layout. When a field test piece is appropriate, measure its resulting offset and reach before repeating the layout.

Before bending

• Confirm the bender supports the conduit material and size.
• Use the tool's mark and shrink conventions consistently; allow for the stated springback method.
• Keep both bends in the same plane and check the final rise and parallel runs.
• Check the applicable conduit rules for total bend, bend radius and pulling access. This geometric calculation does not establish code compliance.

Frequently Asked Questions

Is travel the horizontal distance?

No. Travel follows the sloping segment; horizontal run is its projection. For a 4-in rise at 30°, they are 8 in and about 6.928 in respectively in the ideal model.

Why does the tool's shrink table differ from trigonometry?

The ideal model ignores bend radius and marking conventions. A manufacturer's rounded field factors are intended for its described bending procedure. Use one method consistently and check the actual tool instructions.

Is the calculated travel my total cut length?

No. A complete developed length includes all straight tangent lengths, bend arcs and any required end allowances. Travel between ideal offset corners is only one geometric quantity.