Imperial Washer Size Chart

WHAT IS THE PURPOSE OF WASHERS AND WHY ARE THEY USED?

LOAD DISTRIBUTION

The primary purpose of washers is to reduce the risk of damage and distribute the load of the threaded fastener with which they are used.

Threaded fasteners stress the material that they are driven into. For example, driving a screw into a wooden surface may crack the surface and damage the internal grain structure.

Not all materials require washers, but for wood and other softer materials, it is generally safer to incorporate washers to spread the load over a larger area.

SPACING

Washers can also be used as spacers.

Dimensions shown are in Inches, if you wish to convert to mm, please use our universal converter.

We also have information on Metric Washers.

IMPERIAL - FLAT WASHER DIMENSIONS - BS3410

Nominal Size	Inside Dia (d1)	Outside Dia (d2)	Thickness (h)
1/4"	0.281	0.625	0.048
5/16"	0.344	0.750	0.064
3/8"	0.406	0.875	0.064
7/16"	0.469	1.000	0.080
1/2"	0.531	1.125	0.080
5/8"	0.656	1.375	0.104
3/4"	0.781	1.625	0.104

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IMPERIAL - SPRING WASHER DIMENSIONS - BS3410

Nominal Size	Inside Dia (d1)	Outside Dia (d2)	Section Size (w x t)
1/4"	0.255	0.489	0.109 x 0.062
5/16"	0.318	0.587	0.125 x 0.078
3/8"	0.382	0.684	0.141 x 0.094
7/16"	0.445	0.784	0.156 x 0.109
1/2"	0.508	0.884	0.172 x 0.125
5/8"	0.634	1.099	0.219 x 0.156
3/4"	0.760	1.324	0.266 x 0.188

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IMPERIAL - INTERNAL TOOTH WASHER DIMENSIONS - BS3410

Nominal Size	Inside Dia (d1)	Outside Dia (d2)
1/4"	0.255	0.478
5/16"	0.320	0.594
3/8"	0.384	0.692
7/16"	0.448	0.760
1/2"	0.513	0.878

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IMPERIAL - EXTERNAL TOOTH WASHER DIMENSIONS - BS3410

Nominal Size	Inside Dia (d1)	Outside Dia (d2)
1/4"	0.255	0.502
5/16"	0.320	0.597
3/8"	0.384	0.692
7/16"	0.448	0.760
1/2"	0.513	0.892