Steel Strength

A safe’s first line of defense is its door and five walls. Door and wall steel thickness determines a safe’s ability to protect. The more steel the greater protection. Please review the graph below.

Steel Bending Strength Increase

Material Thickness Material Thickness Decimals Steel Weight by S.F. lbs. 14-Gauge (.075) 12-Gauge (.106) 11-Gauge (.120) 10-Gauge (.135) 3/16"
14-Gauge 0.075 3.125   2.86x 4.15x 5.9x 15.9x 37.5x 126.5x 299.9x
12-Gauge 0.106 4.375 .35x   1.45x 2.06x 5.59x 13.12x 44.3x 105.0x
11-Gauge 0.120 5.00 .24x .69x   1.42x 3.85x 9.04x 30.5x 72.3x
10-Gauge 0.135 5.625 .17x .48x .70x   2.7x 6.35x 20.25x 49.9x
3/16" 0.188 7.66 .06x .18x .26x .39x   2.35x 7.04x 18.8x
1/4" 0.250 10.21 .03x .08x .11x .16x .43x   3.38x 8.0x
3/8" 0.375 15.32 .01x .02x .03x .05x .13x .30x   2.37x
1/2" 0.500 20.42 .003x .01x .015x .02x .05x .12x .42x  

The graph illustrates a general rule of steel strength. The bending strength of steel increases by approximately the square of its thickness.


  • 12-gauge (.106) steel is 2.86 times stronger than 14-gauge (.075), even though it is only .031 thicker.
  • A safe made from 12-gauge (.106) steel is almost 3 times stronger than one constructed from 14-gauge (.075) steel.
  • A safe door made from 10-gauge steel is 2.06 times stronger than one made from 12-gauge.
  • A safe door made from 10-gauge steel is 5.9 times stronger than one made from 14-gauge.


Thicker steel makes a huge difference in the protective ability of a safe. Steel is heavy and expensive but the foundation of any quality safe.


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