What is 'gain' in conduit bending?

Gain (also called 'take-up' or 'deduction') is the amount of conduit saved when making a bend compared to running two straight pieces around a corner. For a 90° bend, the gain equals the bend radius — because the curved path is shorter than two straight legs meeting at a right angle. You must subtract the gain from your measured lengths to get the correct cutting length, otherwise the conduit will be too long.

What is the minimum bend radius for conduit?

BS 7671 and conduit manufacturers specify minimum bend radii: 16mm conduit = 50mm radius, 20mm = 75mm, 25mm = 100mm, 32mm = 125mm. These minimums prevent kinking and ensure cables can be drawn through without damage. Using a proper conduit bending machine (hickey or hydraulic bender) with the correct former ensures the radius is maintained. Hand-bending risks kinks and flat spots.

How do I calculate an offset bend?

An offset uses two equal-angle bends (typically 45°) to shift the conduit run by a set distance. The travel (distance between bends along the conduit) = offset distance ÷ sin(bend angle). For 45° bends: travel = offset × 1.414 (√2). For 30° bends: travel = offset × 2. The shrinkage (how much shorter the overall run becomes) = offset ÷ tan(bend angle). Mark the first bend, measure the travel distance along the conduit, and mark the second.

When would I use a saddle bend?

A saddle bend (also called a 'bridge' or 'crossover') is used when the conduit run needs to pass over an obstacle — such as another conduit, a pipe, or a structural member. It consists of three bends: the centre bend (typically 60°) and two equal outer bends (30° each). The saddle lifts the conduit over the obstacle and returns it to the original level. Precise marking is essential — measure the obstacle depth and width carefully.

How many bends can I have in a conduit run?

Good practice limits a conduit run to two 90° bends (or equivalent) between draw-in points. More bends make cable pulling extremely difficult and risk damaging cable insulation. If your route requires more than two 90° bends, install an additional draw-in box or inspection fitting. Each 90° bend approximately doubles the pulling force required. For long runs with multiple bends, consider using trunking instead.

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Conduit Bending Calculator

Calculate conduit bend dimensions, gain, marking positions, and total conduit length for 90-degree, 45-degree, offset, saddle, and kick-back bends.

Bend TypeType of conduit bend

Conduit SizeDetermines minimum bend radius

Run Length A (before bend)

First straight section

Run Length B (after bend)

Second straight section

How We Calculate This

This calculator determines conduit bend dimensions, marking positions, and total conduit length for common bend types used in electrical installation.