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Pipe Offset Calculator

Calculate the travel (cut length) and advance (run) for pipe offsets using standard fitting angles.

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Table of Contents

Calculator Tool Offset Formulas Multiplier Constants Fitting Deductions Step-by-Step Guide Frequently Asked Questions Related Calculators

Calculator Inputs

in

Center-to-center distance

in

Distance from center to face of fitting

Results

Travel Length (T)
14.14
inches

Center-to-center connecting pipe length

Advance / Run (R)
10.00 in
True Cut Length
--

Offset Formulas

A pipe offset forms a right triangle. If you know the offset distance and the fitting angle, you can use basic trigonometry to find the travel (hypotenuse) and the run (adjacent side).

Travel (T) = Offset ÷ sin(Angle)

Run (R) = Offset ÷ tan(Angle)

Alternative: Travel = Offset × Cosecant(Angle)

Don't forget Fitting Allowance (Makeup)!

The calculated "Travel" is the center-to-center distance. To get the actual length of pipe you need to cut (the end-to-end cut length), you must subtract the fitting allowance (makeup) for both fittings from the calculated travel length.

Fitting Allowance & Cut Length Deduction

When cutting pipe for an offset, calculating center-to-center travel length is only the first step. You must subtract the fitting allowance (takeoff/makeup) for both fittings to determine the actual pipe cut length.

True Cut Length Formula

Cut Length = Travel (Center-to-Center) - (2 × Fitting Allowance)

Common 45° Elbow Fitting Allowance Estimates

Nominal Pipe Size Copper Soldered 45° PVC DWV 45° (1/8 Bend) Black Iron / Malleable 45°
1/2 inch 3/8 in (0.375") 3/8 in (0.375") 1/2 in (0.500")
3/4 inch 7/16 in (0.4375") 1/2 in (0.500") 5/8 in (0.625")
1 inch 1/2 in (0.500") 5/8 in (0.625") 3/4 in (0.750")
1-1/2 inch 11/16 in (0.6875") 1-1/8 in (1.125") 1 in (1.000")
2 inch 13/16 in (0.8125") 1-3/8 in (1.375") 1-1/4 in (1.250")

*Note: Always verify exact fitting dimensions with manufacturer specification sheets for precise pre-fabrication cutting.

Step-by-Step Pipe Offset Guide

Follow these professional trade steps when laying out and fabricating pipe offsets in the field:

  1. 1

    Measure the Offset Distance

    Measure the exact perpendicular distance from the centerline of the existing pipe to the centerline of the target position where the parallel pipe run needs to be re-routed.

  2. 2

    Select Fitting Angle & Multiplier

    Choose the appropriate elbow angle for your offset (45° is standard). Use the multiplier constant 1.414 for 45°, 2.613 for 22.5°, or 1.155 for 60°.

  3. 3

    Calculate Travel (Center-to-Center)

    Multiply the Offset by the Travel Constant: Travel = Offset × 1.414 for 45° bends. For rolling offsets, first calculate True Offset = √(Roll² + Set²) before applying the multiplier.

  4. 4

    Deduct Fitting Allowance & Cut Pipe

    Subtract the fitting allowance for both fittings from the calculated travel length to get the true end-to-end cut length. Cut the pipe cleanly and deburr edges before fitting assembly.

Frequently Asked Questions

How do you calculate travel for a 45 degree pipe offset?

To calculate travel for a 45° offset, multiply your offset distance by 1.414 (which is 1 / sin(45°)). For example, if your offset is 10 inches, the center-to-center travel is 10 × 1.414 = 14.14 inches.

What is the difference between a simple offset and a rolling offset?

A simple offset shifts a pipe run in a single plane (e.g., horizontally or vertically only). A rolling offset shifts the pipe in two planes simultaneously (e.g., both up and over). A rolling offset uses both a Set (vertical height) and a Roll (horizontal distance) to find the True Offset using √(Roll² + Set²).

What is fitting allowance or makeup?

Fitting allowance (also called takeoff or makeup) is the distance from the center of a fitting to the face or shoulder where the pipe seats inside the fitting socket. Subtracting fitting allowance for both fittings yields the exact pipe piece cut length needed for tight, leak-free assembly.

Can I use this calculator for electrical conduit offsets?

Yes! Electricians and conduit benders use the exact same trigonometric principles and multiplier constants (e.g. 1.414 for 45°, 2.000 for 30°, 2.613 for 22.5°) to calculate saddle and offset shrink and travel lengths when bending EMT, PVC, or Rigid conduit.

Offset Definitions

  • Offset (O): The perpendicular distance between the centerlines of the two parallel pipes you are connecting.
  • Travel (T): The center-to-center length of the diagonal pipe connecting the two fittings. (Also known as the hypotenuse).
  • Rolling Offset: An offset that changes direction both horizontally and vertically simultaneously.
  • True Offset: The diagonal distance of the offset itself, calculated as √(Roll² + Set²).