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    Technical Info

    At Birmingham Fastener, we aim to provide you with the knowledge and tools for your project. Our constantly expanding Fastener Learning Hub is full of information and insights for a variety of industries. View bolt length charts, read product comparisons, and find answers to your questions about fasteners.

    SAE Flat Washer Dimensions

    SAE Flat Washer Dimensions Per ASME B18.21.1

    Size Inside Diameter (ID) Outside Diameter (OD) Thickness (TH)
    Tolerance Tolerance
    Basic Plus Minus Basic Plus Minus Max Min
    #4 0.125 0.008 0.005 0.312 0.008 0.005 0.040 0.025
    #6 0.156 0.008 0.005 0.375 0.015 0.005 0.065 0.036
    #8 0.188 0.008 0.005 0.438 0.015 0.005 0.065 0.036
    #10 0.219 0.008 0.005 0.500 0.015 0.005 0.065 0.036
    #12 0.250 0.015 0.005 0.562 0.015 0.005 0.080 0.051
    1/4 0.281 0.015 0.005 0.625 0.015 0.005 0.080 0.051
    5/16 0.344 0.015 0.005 0.688 0.015 0.007 0.080 0.051
    3/8 0.406 0.015 0.005 0.812 0.015 0.007 0.080 0.051
    7/16 0.469 0.015 0.005 0.922 0.015 0.007 0.080 0.051
    1/2 0.531 0.015 0.005 1.062 0.030 0.007 0.121 0.074
    9/16 0.594 0.015 0.005 1.156 0.030 0.007 0.121 0.074
    5/8 0.656 0.030 0.007 1.312 0.030 0.007 0.121 0.074
    3/4 0.812 0.030 0.007 1.469 0.030 0.007 0.160 0.108
    7/8 0.938 0.030 0.007 1.750 0.030 0.007 0.160 0.108
    1 1.062 0.030 0.007 2.000 0.030 0.007 0.160 0.108
    1 1/8 1.250 0.030 0.007 2.250 0.030 0.007 0.160 0.108
    1 1/4 1.375 0.030 0.007 2.500 0.030 0.007 0.192 0.136
    1 3/8 1.500 0.030 0.007 2.750 0.030 0.007 0.192 0.136
    1 1/2 1.625 0.030 0.007 3.000 0.030 0.007 0.192 0.136
    1 3/4 1.875 0.045 0.010 3.375 0.045 0.010 0.213 0.153
    2 2.125 0.045 0.010 3.750 0.045 0.010 0.213 0.153

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