Accurate Bend Allowance Calculator for Sheet Metal Fabrication

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What is bend allowance?

The bending allowance is a value used to determine the length of the sheet metal after bending.

It varies based on the material, thickness of the sheet, and type of bending die used.

The bending allowance is a statistical value that is derived from the experience and repeated verification of experienced mold designers over the years.

Mold designers can use the calculation formula directly to obtain the unfolding plate size of the bent structure, which is based on the bending allowance data.

Bend allowance calculation method

Bend allowance and bend deduction calculations are methods that can be used to determine the length of sheet metal raw materials in the flat form, so as to obtain the desired size of the bending part.

Bend allowance calculation method:

The following equation is used to determine the total flattening length when the bending allowance value is used:

Lt = A + B + BA

Wherein:
·Lt is the total flat length
·A and B are shown in the figure
·BA is the bending allowance value

Bend deduction calculation method:

The following equation is used to determine the total flattening length when using the bend deduction value:

Lt = A + B – BD

Wherein:
·Lt is the total flat length
·A and B are shown in the figure
·BD is the bending deduction value

Other calculation methods for determining the flat length of sheet metal raw materials include using a bending allowance chart, the K-factor, and bending calculations.

For new press brake operators who may not know how to calculate the bend allowance, a bend allowance calculator has been created to help make their daily work easier.

To learn more about bend allowances, you can also watch a video on the subject.


Further reading:

Bend allowance chart

Bend allowance chart for SPCC (mild steel)

MaterialThicknessBending angleV openingInner radiusBends Allowance
SPCC0.590V40.50.95
1000.73
1350.3
1750.03
  
SPCC0.590V50.51.03
1000.79
1350.33
1750.03
  
SPCC0.590V60.51.1
1000.85
1350.35
1750.03
  
SPCC0.690V40.51.08
1000.83
1350.35
1750.03
  
SPCC0.690V50.51.15
1000.89
1350.37
1750.03
  
SPCC0.690V60.51.23
1000.95
1350.39
1750.03
  
SPCC0.890V60.51.49
1200.73
1350.47
1500.25
  
SPCC0.890V801.64
1200.81
1350.52
1500.27
  
SPCC0.890V1001.79
1200.88
1350.57
1500.3
  
SPCC190V1002.05
1001.58
1201.01
1350.62
1750.06
SPCC190V801.9
1001.47
1200.93
1350.6
1750.05
SPCC190V601.74
1001.35
1200.86
1350.56
1750.05
SPCC1.290V101.42.31
1001.78
1201.13
1350.73
1750.06
SPCC1.290V81.42.15
1001.66
1201.06
1350.69
1750.06
SPCC1.290V61.42
1001.55
1200.98
1350.64
1750.05
SPCC1.590V61.72.36
1001.82
1201.16
1350.75
1750.06
SPCC1.590V121.72.8
1002.17
1201.38
1350.89
1750.08
SPCC1.590V101.72.65
1002.05
1201.31
1350.85
1750.07
SPCC1.590V81.72.5
1001.94
1201.23
1350.8
1750.07
SPCC290V1023.29
1002.54
1201.62
1351.05
1750.09
SPCC290V1223.44
1002.66
1201.69
1351.1
1750.09
SPCC2.590V183.034.6
1003.56
1202.26
1351.47
1750.12
SPCC2.590V123.034.15
1003.21
1202.04
1351.32
1750.11
SPCC2.590V103.034
1003.09
1201.97
1351.28
1750.11
SPCC390V183.133.135.22
1004.03
1202.57
1351.66
1750.14
SPCC390V123.134.78
1003.69
1202.35
1351.52
1750.13
SPCC390V103.134.63
1003.58
1202.28
1351.48
1750.13

Bend allowance chart for SUS (stainless steel)

MaterialThicknessBending angleV openingInner radiusBends Allowance
SUS0.59040.61.04
1000.79
1200.48
1350.3
1750.04
SUS0.59050.61.15
1000.88
1200.54
1350.33
1750.04
SUS0.59060.61.27
1001.13
1200.59
1350.37
1750.04
SUS0.69040.61.16
1000.88
1200.54
1350.34
1750.04
SUS0.69050.61.27
1000.97
1200.59
1350.37
1750.04
SUS0.69060.61.38
1001.05
1200.64
1350.4
1750.05
SUS0.89041.11.4
1001.06
1200.65
1350.4
1750.05
SUS0.89051.11.51
1001.15
1200.7
1350.44
1750.05
SUS0.89061.11.62
1001.23
1200.75
1350.47
1750.06
SUS19061.91.87
1001.42
1200.87
1350.54
1750.07
SUS19081.92.1
1001.6
1200.98
1350.61
1750.07
SUS1.29061.62.1
1001.59
1200.97
1350.61
1750.07
SUS1.29081.62.32
1001.76
1201.08
1350.67
1750.08
SUS1.290101.62.54
1001.93
1201.18
1350.74
1750.09
SUS1.59082.12.68
1002.03
1201.24
1350.77
1750.09
SUS1.590102.12.9
1002.2
1201.35
1350.84
1750.1
SUS29010 3.49
1002.65
1201.62
1351.01
1750.12
SUS29012 3.7
1002.82
1201.72
1351.07
1750.13

Bend allowance chart for SPHC (stainless steel)

MaterialThicknessBending angleV openingInner radiusBends Allowance
SPHC190V101.862.05
1001.58
1201.01
1350.62
1750.06
SPHC190V81.861.9
1001.47
1200.93
1350.6
1750.05
SPHC190V61.861.74
1001.35
1200.86
1350.56
1750.05
SPHC1.290V101.442.31
1001.78
1201.13
1350.73
1750.06
SPHC1.290V81.442.15
1001.66
1201.06
1350.69
1750.06
SPHC1.290V61.442
1001.55
1200.98
1350.64
1750.05
SPHC1.590V121.742.8
1002.17
1201.38
1350.89
1750.08
SPHC1.590V101.742.65
1002.05
1201.31
1350.85
1750.07
SPHC1.590V81.742.5
1001.94
1201.23
1350.8
1750.07
SPHC290V122.013.44
1002.66
1201.69
1351.1
1750.09
SPHC290V102.013.29
1002.54
1201.62
1351.05
1750.09
SPHC2.590V1834.6
1003.25
1202.26
1351.47
1750.12
SPHC2.590V1234.15
1003.21
1202.04
1351.32
1750.11
SPHC2.590V1034
1003.09
1201.97
1351.28
1750.11
SPHC390V183.15.22
1004.03
1202.57
1351.66
1750.14
SPHC390V123.14.78
1003.69
1202.35
1351.52
1750.13
SPHC390V103.14.63
1003.58
1202.28
1351.48
1750.13

Bend allowance chart for SECC (galvanized steel sheet)

MaterialThicknessBending angleV openingInner radiusBends Allowance
SECC190V101.92.05
1001.58
1201.01
1350.62
1750.06
SECC190V81.91.9
1001.47
1200.93
1350.6
1750.05
SECC190V61.91.74
1001.35
1200.86
1350.56
1750.05
SECC1.290V101.42.31
1001.78
1201.13
1350.73
1750.06
SECC1.290V81.42.15
1001.66
1201.06
1350.69
1750.06
SECC1.290V61.42
1001.55
1200.98
1350.64
1750.05
SECC1.590V121.72.8
1002.17
1201.38
1350.89
1750.08
SECC1.590V101.72.65
1002.05
1201.31
1350.85
1750.07
SECC1.590V81.72.5
1001.94
1201.23
1350.8
1750.07
SECC290V1223.44
1002.66
1201.69
1351.1
1750.09
SECC290V1023.29
1002.54
1201.62
1351.05
1750.09
SECC2.590V183.034.6
1003.56
1202.26
1351.47
1750.12
SECC2.590V123.034.15
1003.21
1202.01
1351.32
1750.11
SECC2.590V103.034
1003.09
1201.97
1351.28
1750.11
SECC390V183.135.22
1004.03
1202.57
1351.66
1750.14
SECC390V123.131.78
1003.69
1202.35
1351.52
1750.13
SECC390V103.134.63
1003.58
1202.28
1351.48
1750.13

Bend allowance chart for aluminum plate

MaterialThicknessBending angleV openingInner radiusBends Allowance
AL0.89040.61.15
1000.81
1200.5
1350.36
1750.03
AL0.89050.61.2
1000.85
1200.52
1350.37
1750.03
AL0.89060.61.25
1000.88
1200.54
1350.39
1750.03
AL19060.61.49
1001.05
1206.5
1350.46
1750.04
AL19080.61.59
1001.13
1200.69
1350.5
1750.04
AL1.29060.91.73
1001.22
1200.75
1350.54
1750.04
AL1.29080.91.82
1001.29
1200.79
1350.57
1750.05
AL1.59081.22.18
1001.54
1200.95
1350.68
1750.06
AL1.590101.22.28
1001.61
1200.99
1350.71
1750.06
AL1.590121.22.38
1001.68
1201.03
1350.74
1750.06
AL290141.63.07
1002.17
1201.3
1350.93
1750.08
AL290121.62.98
1002.11
1201.34
1350.95
1750.08
AL290181.63.25
1002.3
1201.42
1351.01
1750.08
AL2.590182.43.89
1002.75
1201.7
1351.21
1750.1
AL390182.54.5
1003.18
1201.96
1351.4
1750.1
AL3.290182.54.74
1003.35
1202.06
1351.47
1750.12
AL490404.66.77
1004.79
1202.95
1352.11
1750.17
AL6.8908009.412.09
1008.55
1205.27
1353.76
1750.31

Before you go.…

About The Author

As the founder of MachineMfg, I have dedicated over a decade of my career to the metalworking industry. My extensive experience has allowed me to become an expert in the fields of sheet metal fabrication, machining, mechanical engineering, and machine tools for metals. I am constantly thinking, reading, and writing about these subjects, constantly striving to stay at the forefront of my field. Let my knowledge and expertise be an asset to your business. Reach me at [email protected]

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