SAE Flat Washers

Bolt Size Outside Diameter Inside Diameter Thickness Approximate Number per 50 Pounds
Nominal Max Min Nominal Max Min American Standard (Gauge) Max Min
4 5/16 0.320 0.307 1/8 0.133 0.120 (1/32) .040 .025 83300
6 3/8 0.390 0.370 5/32 0.164 0.151 18 (3/64) .065 .036 39500
8 7/16 0.453 0.433 3/16 0.196 0.183 18 (3/64) .065 .036 29500
10 1/2 0.515 0.495 7/32 0.227 0.214 18 (3/64) .065 .036 22750
3/16 9/16 0.577 0.557 1/4 0.265 0.245 18 (3/64) .065 .036  
12 9/16 0.577 0.557 1/4 0.265 0.245 16 (1/16) .080 .051 14700
1/4 5/8 0.640 0.620 9/32 0.296 0.276 16 (1/16) .080 .051 11100
5/16 11/16 0.703 0.681 11/32 0.359 0.339 16 (1/16) .080 .051 9750
3/8 13/16 0.827 0.805 13/32 0.419 0.401 16 (1/16) .080 .051 7000
7/16 59/64 0.937 0.915 15/32 0.484 0.464 16 (1/16) .080 .051 5500
1/2 1-1/16 1.092 1.055 17/32 0.546 0.526 13 (3/32) .121 .074 2800
9/16 1-3/16 1.186 1.149 19/32 0.609 0.589 13 (3/32) .121 .074 2250
5/8 1-5/16 1.342 1.305 21/32 0.686 0.649 13 (3/32) .121 .074 1850
3/4 1-1/2 1.499 1.462 13/16 0.842 0.805 10 (9/64) .160 .108 1050
7/8 1-3/4 1.780 1.743 15/16 0.968 0.931 10 (9/64) .160 .108 775
1 2 2.030 1.993 1-1/16 1.092 1.055 10 (9/64) .160 .108 585
1-1/8 2-1/4 2.280 2.243 1-3/16 1.280 1.243 10 (9/64) .160 .108 460
1-1/4 2-1/2 2.530 2.493 1-5/16 1.405 1.368 9 (5/32) .192 .136 335
1-3/8 2-3/4 2.780 2.743 1-7/16 1.530 1.493 9 (5/32) .213 .136 275
1-1/2 3 3.030 2.993 1-9/16 1.655 1.618 9 (5/32) .213 .153 230