Piping
Pipe offset calculator
In short
A pipe offset shifts a line with two elbows of the same angle. From the axis-to-axis offset H and the elbow angle α, the calculation gives the travel T = H / sin α, the take-out of each elbow E = R × tan(α / 2) and the cut length L = T − 2E − 2j.
Calculation
Example calculated with the tool’s default values.
Inputs
- Pipe
- DN50 · 60.3 × 2.9 mm
- I know
- Angle
- Offset (axis to axis)
- 200 mm
- Elbow angle
- 45°
- Elbow radius
- Bought long-radius elbow (EN 10253-2 3D or ASME B16.9 LR per pipe)
- Root gap
- 0 mm
- Elbow to cut from
- Smallest that fits
- Marks around
- 16
- Then a 90° drop
- No
Results
- Cut length
- 219.9 mm
Worked example
Every value in this section belongs to the example, calculated with the tool’s default values.
Other results of the example
- Travel
- 282.8 mm
- Run
- 200.0 mm
- Elbow take-out
- 31.5 mm
- Radius used
- 76.0 mmEN 10253-2 3D elbow
- Run between free elbow faces
- 263.0 mm
Step-by-step calculation
Travel
T = H / sin α
200.0 / sin 45° = 282.8 mm
Elbow take-out
E = R × tan(α / 2)
76.0 × tan 22.50° = 31.5 mm
Cut length
L = T − 2E − 2j
282.8 − 63.0 − 0.0 = 219.9 mm
Run between faces
X = H / tan α + 2E
200.0 + 63.0 = 263.0 mm
How to use it
- Pick the pipe: outside diameter and wall thickness.
- Say what you know: the elbow angle, the pipe length between the elbows, or the run X with the offset H.
- Enter the axis-to-axis offset and the elbow radius: long radius (1.5 D) or short radius (1 D).
- Read the cut length.
Frequently asked questions
What is the pipe offset formula?
The travel between the two elbows is T = H / sin α, where H is the axis-to-axis offset and α the elbow angle. Then subtract the take-out of each elbow, E = R × tan(α / 2), and the root gap j: cut length L = T − 2E − 2j.
What is the 45 degree offset formula?
With two 45° elbows and a 200 mm offset, the travel is 200 / sin 45° = 282.8 mm. For a 60.3 mm pipe with long radius elbows (R = 1.5 × OD), each elbow takes out 37.5 mm, so the cut length is 282.8 − 74.9 = 207.9 mm with no root gap.
Does it work for angles other than 45°?
Yes: the same formula applies to any angle from 1° to 90°. When the angle is neither 45° nor 90°, each elbow is cut down from a 45° or 90° elbow, and the tool then gives the elbow cut layout.
What if I know the spool length but not the angle?
Enter the offset and the pipe length between the elbows: the angle is worked out by the calculation. A spool of 0 means two elbows welded to each other. You can also start from the run X, measured between the elbow vertices or between the free elbow faces.
Limits
Indicative results. Elbow radii (1.5 D and 1 D) are approximated on the pipe outside diameter, from EN 10253-2 and ASME B16.9: check the dimension on your elbows before cutting.
Sources
- Géométrie du dévoiement : Trigonométrie du triangle rectangle (T = S / sin α, A = S / tan α, E = R × tan(α / 2))
- EN 10253-2:2021+A1:2026 (raccords à souder bout à bout) : Coudes 2D/3D (rayon R), tés égaux (F), réductions (L) ; tableaux Zickwolff, consultés le 08/11/2026 (link)