Pipe Elbow Calculator

Determine exact center-to-face takeout dimensions, cut-back allowances, and weld gap adjustments for butt-weld pipe fittings.

Nominal Pipe Size (NPS)

Elbow Angle

Radius Standard

Root Gap per Joint (Inches) 1/8" standard

Deducted from pipe nipple length for weld fit-up

Center-to-Face (Takeout)

3.000 in

76.2 mm

Nipple Takeout (w/ Gap) 2.875 in Deduct from center mark

Radius of Bend 3.0 in (LR) Centerline radius

Standard Takeout Formula For any angle $ heta$: Takeout = Radius × tan(θ / 2). For a standard 90° LR elbow, tan(45°) = 1.0, making takeout simply 1.5 × NPS.

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Buttweld Pipe Elbow Takeout Formulas

In pipefitting, "takeout" is the distance from the intersection center point of the two pipe centerlines to the weld bevel face of the fitting:

90° Long Radius (LR): Center-to-Face = 1.5 × NPS (e.g. 4" NPS = 6.0" takeout)
90° Short Radius (SR): Center-to-Face = 1.0 × NPS (e.g. 4" NPS = 4.0" takeout)
45° Long Radius: Center-to-Face = 1.5 × NPS × tan(22.5°) = 1.5 × NPS × 0.4142 = 0.6213 × NPS (or 5/8" per inch of NPS)

Frequently Asked Questions

What is the takeout for a 45° LR elbow?

The formula is 1.5 × NPS × 0.4142. A fast mental rule of thumb is 5/8" per inch of nominal pipe size (e.g. 2" pipe = 1-1/4" takeout).

When are Short Radius (SR) elbows used?

Short radius elbows (1.0D) are used strictly in tight quarters and skid-mounted packaging where clearance is limited, but cause higher friction pressure drop.

Why must root gap be deducted?

Buttweld joints require a 3/32" to 1/8" root gap between pipe and fitting for full-penetration welding. Subtracting the gap from pipe cut length ensures center-to-center dimensions remain exact.