Ball Size
MILLIMETERS TO INCHES
MM INCHES MM INCHES
0.50 0.0196850 18.50 0.7283450
1.00 0.0393700 19.00 0.7480300
1.50 0.0590550 19.50 0.7677150
2.00 0.0787400 20.00 0.7874000
2.50 0.0984250 20.50 0.8070850
3.00 0.1181100 21.00 0.8267700
3.50 0.1377950 21.50 0.8464550
4.00 0.1574800 22.00 0.8661400
4.50 0.1771650 22.50 0.8858250
5.00 0.1968500 23.00 0.9055100
5.50 0.2165350 23.50 0.9251950
6.00 0.2362200 24.00 0.9448800
6.50 0.2559050 24.50 0.9645650
7.00 0.2755900 25.00 0.9842500
7.50 0.2952750 25.50 1.0039350
8.00 0.3149600 26.00 1.0236200
8.50 0.3346450 26.50 1.0433050
9.00 0.3543300 27.00 1.0629900
9.50 0.3740150 27.50 1.0826750
10.00 0.3937000 28.00 1.1023600
10.50 0.4133850 28.50 1.1220450
11.00 0.4330700 29.00 1.1417300
11.50 0.4527550 29.50 1.1614150
12.00 0.4724400 30.00 1.1811000
12.50 0.4921250 30.50 1.2007850
13.00 0.5118100 31.00 1.2204700
13.50 0.5314950 31.50 1.2401550
14.00 0.5511800 32.00 1.2598400
13.00 0.5118100 32.50 1.2795250
14.00 0.5511800 33.00 1.2992100
14.50 0.5708650 33.50 1.3188950
15.00 0.5905500 34.00 1.3385800
15.50 0.6102350 34.50 1.3582650
16.00 0.6299200 35.00 1.3779500
16.50 0.6496050 35.50 1.3976350
17.00 0.6692900 36.00 1.4173200
17.50 0.6889750 36.50 1.4370050
18.00 0.7086600 37.00 1.4566900
Ball Size
INCHES TO MILLIMETERS
INCHES DECIMAL MILLIMETERS
1/32 0.03125 0.79375
3/64 0.04688 1.19063
1/16 0.06250 1.58750
5/64 0.07813 1.98438
3/32 0.09375 2.38125
1/8 0.12500 3.17500
5/32 0.15625 3.96875
3/16 0.18750 4.76250
7/32 0.21875 5.55625
¼ 0.25000 6.35000
9/32 0.28125 7.14375
5/16 0.31250 7.93750
11/32 0.34375 8.73125
3/8 0.37500 9.52500
13/32 0.40625 10.31875
7/16 0.43750 11.11250
15/32 0.46875 11.90625
½ 0.50000 12.70000
17/32 0.53125 13.49375
9/16 0.56250 14.28750
5/8 0.62500 15.87500
11/16 0.68750 17.46250
¾ 0.75000 19.05000
13/16 0.81250 20.63750
7/8 0.87500 22.22500
1 1.00000 25.40000
1 1/16 1.06300 27.00020
1 1/8 1.12500 28.57500
1 3/16 1.18750 30.16250
1 ¼ 1.25000 31.75000
1 5/16 1.31250 33.33750
1 3/8 1.37500 34.92500
1 7/16 1.43750 36.51250
1 ½ 1.50000 38.10000
1 5/8 1.62500 41.27500
1 ¾ 1.75000 44.45000
1 7/8 1.87500 47.62500
2 2.00000 50.80000
Grade Tolerances Semi-Precision Balls
Grade Tolerance (inches)
100 ± .0001
200 ± .0002
500 ± .0005
1000 ± .001
2000 ± .002
Grade Tolerances Precision Balls
Grade Tolerance (inches)
3 ± .000003
5 ± .000005
10 ± .000010
25 ± .000025
50 ± .000050
Number of Balls per Pound (approx.)  
Size Size                  
Inches Decimal 302ss 316ss 420ss 430ss 440ss Chrome Carbon Brass Aluminum
1/32 0.03125 218,819 217,299 223,508 225,116 227,571 221,138 220,360 204,517 625,821
1/16 0.06250 27,352 27,162 27,938 28,139 28,446 27,642 27,545 25,565 78,228
3/32 0.09375 8,104 8,048 8,278 8,338 8,429 8,190 8,161 7,575 23,179
1/8 0.12500 3,419 3,395 3,492 3,517 3,556 3,455 3,443 3,196 9,778
5/32 0.15625 1,751 1,738 1,788 1,801 1,821 1,769 1,763 1,636 5,007
3/16 0.18750 1,013 1,006 1,035 1,042 1,054 1,024 1,020 947 2,897
7/32 0.21875 638 634 652 656 663 645 642 596 1,825
1/4" 0.25000 427 424 437 440 444 432 430 399 1,222
9/32 0.28125 300 298 307 309 312 303 302 281 858
5/16 0.31250 219 217 224 225 228 221 220 205 626
11/32 0.34375 164 163 168 169 171 166 166 154 470
3/8" 0.37500 127 126 129 130 132 128 128 118 362
7/16 0.43750 80 79 81 82 83 81 80 75 228
Inches Decimal 302ss 316ss 420ss 430ss 440ss Chrome Carbon Brass Aluminum
1/2 0.50000 53.4 53.1 54.6 55.0 55.6 54.0 53.8 49.9 152.8
17/32 0.53125 44.5 44.2 45.5 45.8 46.3 45.0 44.9 41.6 127.4
9/16 0.56250 37.5 37.3 38.3 38.6 39.0 37.9 37.8 35.1 107.3
5/8 0.62500 27.4 27.2 27.9 28.1 28.4 27.6 27.5 25.6 78.2
11/16 0.68750 20.6 20.4 21.0 21.1 21.4 20.8 20.7 19.2 58.8
3/4 0.75000 15.8 15.7 16.2 16.3 16.5 16.0 15.9 14.8 45.3
7/8 0.87500 10.0 9.9 10.2 10.3 10.4 10.1 10.0 9.3 28.5
Inches Decimal 302ss 316ss 420ss 430ss 440ss Chrome Carbon Brass Aluminum
1 1.00000 6.68 6.63 6.82 6.87 6.94 6.75 6.72 6.24 19.10
1-1/16 1.06250 5.57 5.53 5.69 5.73 5.79 5.63 5.61 5.20 15.92
1-1/8 1.12500 4.69 4.66 4.79 4.83 4.88 4.74 4.72 4.38 13.41
1-1/4 1.25000 3.42 3.40 3.49 3.52 3.56 3.46 3.44 3.20 9.78
1-5/16 1.31250 2.95 2.93 3.02 3.04 3.07 2.98 2.97 2.76 8.45
1-3/8 1.37500 2.57 2.55 2.62 2.64 2.67 2.60 2.59 2.40 7.35
1-1/2 1.50000 1.98 1.96 2.02 2.04 2.06 2.00 1.99 1.85 5.66
1-3/4 1.75000 1.25 1.24 1.27 1.28 1.30 1.26 1.25 1.16 3.56
Inches Decimal 302ss 316ss 420ss 430ss 440ss Chrome Carbon Brass Aluminum
2 2.00000 0.835 0.829 0.853 0.859 0.868 0.844 0.841 0.780 2.387
2-1/4 2.25000 0.586 0.582 0.599 0.603 0.610 0.592 0.590 0.548 1.677
2-1/2 2.50000 0.427 0.424 0.437 0.440 0.444 0.432 0.430 0.399 1.222
2-3/4 2.75000 0.321 0.319 0.328 0.330 0.334 0.325 0.323 0.300 0.918
3 3.00000 0.247 0.246 0.253 0.254 0.257 0.250 0.249 0.231 0.707