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REBAR & STEEL · REBAR CUTTING LENGTH CALCULATOR

Cutting Length of L Bar

Cutting length of an L bar = A + B − one 90° bend deduction. A 12 mm bar with legs of 1,500 mm and 300 mm, bent on a 4d former, loses about 25 mm (2.07d) at the bend, so its cutting length is 1,775 mm.

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Bar
Dimensions (outside)
mm
mm
Bar shapeA 1500 mmB 300 mmCutting length 1,775 mm × 20myconstructioncalculator.comNot to scale
Diagram updates as you type.

Results

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Cutting length per bar
1,775mm
Total length35.5 m
Total weight31.5 kg
90° bend deduction25 mm (2.07 db)

Dimensions are outside (out-to-out) as on a BS 8666 / ACI 315 bar schedule. Check your fabricator’s bending conventions.

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Working
  1. Bar 12.0 mm, bend diameter 4.0 db
  2. Cutting length = A + B − 1 bend deduction = 1,500 + 300 − 25 = 1,775 mm
  3. × 20 bars = 35.50 m
Results are estimates for planning and material ordering only. They are not a substitute for structural design or approval by a qualified engineer. Read the full disclaimer.
Formula


Bend deduction (90°)   k = 2(r + d) − (π/2)(r + d/2),   r = bend diameter ÷ 2
L bar                  = A + B − k


Worked Example


A 12 mm L bar, legs 1,500 mm and 300 mm outside, 4d former (48 mm, r = 24 mm):


    

  1. k = 2 × (24 + 12) − 1.5708 × (24 + 6) = 72 − 47.1 = 24.9 mm (2.07d)
    2. 

  2. Cutting length = 1,500 + 300 − 24.9 = 1,775 mm
    3. 



90° Bend Deduction by Bar Size






Bar
4d former
6d former
7d former






8 mm
16.6 mm
20.0 mm
21.7 mm




10 mm
20.7 mm
25.0 mm
27.2 mm




12 mm
24.9 mm
30.0 mm
32.6 mm




16 mm
33.2 mm
40.0 mm
43.5 mm




20 mm
41.5 mm
50.0 mm
54.3 mm




25 mm
51.8 mm
62.6 mm
67.9 mm






BS 8666 requires at least 7d for bars of 20 mm and larger; ACI uses 6d for #3 to #8 main bars.


More Cutting Lengths
Frequently Asked Questions
Why is a bend deduction taken off?
Bar schedules give outside dimensions. Around a bend the bar takes a curved, shorter path than the two outside lines meeting at a square corner, so adding the outside legs overstates the length. The difference is the bend deduction.
How much is the deduction for a 90° bend?
Exactly 2(r + d) − (π/2)(r + d/2), where r is the bend radius. On a 4d former that is 2.07d, which is why site rules use 2d per 90° bend. On larger formers it grows: 2.50d at 6d and 2.72d at 7d.
What is the 45°, 90° and 135° bend deduction rule?
Many Indian site guides use 1d for a 45° bend, 2d for 90° and 3d for 135°. The 2d figure matches a 4d former; for bigger bars bent on 6d or 7d formers, use the exact value in the calculator.
References
  • BS 8666:2020: minimum former diameter 4d up to 16 mm and 7d from 20 mm (grade B500)
  • ACI 318-19 §25.3: minimum bend diameter 6db for #3 to #8 main bars