# Rolling Offset Calculator

Calculate pipe rolling offset travel, true offset, and run for plumbing and pipefitting. Supports 22.5, 45, and 60 degree fittings.

## What this calculates

A rolling offset changes both the vertical and horizontal position of a pipe run at the same time. Instead of making two separate offsets, you connect the pipes with a single diagonal piece. Enter your rise and offset distances to calculate the travel length and true offset.

## Inputs

- **Rise (Vertical Offset)** (in) — min 0 — Vertical distance between the two pipe centerlines
- **Offset (Horizontal Offset)** (in) — min 0 — Horizontal distance between the two pipe centerlines
- **Fitting Angle** — options: 22.5°, 45°, 60° — Angle of the elbow fittings used

## Outputs

- **True Offset** (in) — Diagonal distance between pipe centerlines
- **Travel (Pipe Length)** (in) — Center-to-center length of the connecting pipe
- **Run** (in) — Horizontal distance along the pipe direction
- **True Offset** — formatted as text — In feet and inches
- **Travel** — formatted as text — In feet and inches

## Details

## Rolling Offset Formula

A rolling offset combines a vertical rise and a horizontal offset into one diagonal connection. The math involves two steps:

1. **True offset** = square root of (rise² + offset²)
2. **Travel** = true offset / sin(fitting angle)
3. **Run** = true offset / tan(fitting angle)

### Example: 12" Rise, 18" Offset with 45-degree Fittings

- True offset = sqrt(12² + 18²) = sqrt(144 + 324) = sqrt(468) = 21.633 inches
- Travel = 21.633 / sin(45) = 21.633 / 0.7071 = 30.594 inches
- Run = 21.633 / tan(45) = 21.633 / 1.0 = 21.633 inches

### Choosing Fitting Angles

- **45-degree fittings** are the most common for rolling offsets. The travel calculation is the simplest of the three.
- **22.5-degree fittings** produce a longer, more gradual offset. Good for drainage where you want to maintain flow.
- **60-degree fittings** create a steeper, shorter connection but are less commonly used.

### Tips for Accurate Measurements

Measure rise and offset between the centerlines of the two pipes, not the outside edges. Account for fitting takeout (the distance the fitting itself adds) when cutting your pipe.

## Frequently Asked Questions

**Q: What is a rolling offset in plumbing?**

A: A rolling offset is a pipe connection that changes both the vertical and horizontal position of the pipe at the same time. Instead of using two separate elbows (one for up/down and one for side-to-side), a rolling offset uses two fittings at an angle to make both changes in one shot.

**Q: How do you calculate the travel for a rolling offset?**

A: First calculate the true offset: square root of (rise squared + offset squared). Then divide the true offset by the sine of your fitting angle. For 45-degree fittings, travel = true offset x 1.414. For 22.5-degree fittings, travel = true offset x 2.613.

**Q: What is the multiplier for a 45-degree rolling offset?**

A: The multiplier for a 45-degree offset is 1.414 (which is 1 divided by sin(45), or equivalently the square root of 2). Multiply the true offset by 1.414 to get the travel. For 22.5 degrees the multiplier is 2.613, and for 60 degrees it is 1.155.

**Q: Do I need to account for fitting takeout?**

A: Yes. The travel distance this calculator gives is center-to-center. You need to subtract the fitting takeout (also called fitting allowance) for both fittings from the travel to get the actual cut length of the pipe. Takeout dimensions vary by pipe size and fitting type.

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Source: https://vastcalc.com/calculators/construction/rolling-offset
Category: Construction
Last updated: 2026-04-08