Rolling Offset Calculator
A rolling offset is a conduit bend that changes direction in two planes at once — both vertically and horizontally. It is the most complex common bend in electrical conduit work and the one most likely to be calculated wrong without a tool.
This calculator takes your rise (vertical offset), roll (horizontal offset), and bend angle and returns the true offset distance, the roll angle for positioning your conduit in the bender, the travel distance between marks, and the shrink.
Rolling Offset Formulas
True Offset = √(Rise² + Roll²)
Pythagorean theorem applied to the two offset planes
Roll Angle = arctan(Roll / Rise)
The angle to rotate the conduit in the bender shoe
Travel = True Offset × Multiplier
Distance between bend marks on the conduit
The roll angle tells you how far to rotate the conduit before bending so the offset comes out in the correct diagonal plane. Without this rotation, your offset will be in the wrong direction.
How to Use This Calculator
- Enter the rise — the vertical distance the conduit needs to move. You can use inches, feet-inches, or fractions.
- Enter the roll — the horizontal distance the conduit needs to move.
- Select the bend angle — 30° is standard for most hand benders.
- Read the results — Total Offset is the true diagonal distance. Roll Angle tells you how to position the conduit. Travel is the distance between marks. Shrink is the length adjustment.
Use the unit switcher to toggle between feet-inch-fraction, decimal feet, decimal inches, and metric output.
Frequently Asked Questions
What is a rolling offset in conduit bending?
A rolling offset is a conduit bend that changes direction in two planes simultaneously. Unlike a standard offset that moves conduit up or down only, a rolling offset moves the conduit both vertically (rise) and horizontally (roll) at the same time. It is the most complex common bend in electrical work.
How do you calculate the true offset for a rolling offset?
The true offset is calculated using the Pythagorean theorem: True Offset equals the square root of (rise squared plus roll squared). This gives you the actual diagonal distance the conduit needs to traverse, which is always greater than either the rise or the roll alone.
What is the roll angle and how is it used?
The roll angle is the angle you need to rotate the conduit in the bender shoe so the offset bends in the correct diagonal plane. It is calculated as the arctangent of the roll divided by the rise. You rotate the conduit by this angle before making your bends so the offset comes out in the right direction.