| INSIDE | INSIDE | INSIDE | INSIDE | NUMBER SIZES | WHEAT SHEAF | ||
| Diameter (inches) |
Diameter (mm) |
Circumference (inches) |
Circumference (mm) |
US/Canada (Standard) |
British & Irish (Australian Equivalent) |
Japanese Equivalent |
Swiss Equivalent |
| 0.458 | 11.6 | 1.438 | 36.5 | 0 | |||
| 0.466 | 11.8 | 1.463 | 37.2 | 1/4 | |||
| 0.474 | 12.0 | 1.488 | 37.8 | 1/2 | A | ||
| 0.482 | 12.2 | 1.513 | 38.4 | 3/4 | A 1/2 | ||
| 0.490 | 12.4 | 1.539 | 39.1 | 1 | B | 1 | |
| 0.498 | 12.6 | 1.564 | 39.7 | 1 1/4 | B 1/2 | ||
| 0.506 | 12.9 | 1.589 | 40.4 | 1 1/2 | C | ||
| 0.514 | 13.1 | 1.614 | 41.0 | 1 3/4 | C 1/2 | ||
| 0.522 | 13.3 | 1.639 | 41.6 | 2 | D | 2 | 1.50 |
| 0.530 | 13.5 | 1.664 | 42.3 | 2 1/4 | D 1/2 | ||
| 0.538 | 13.7 | 1.689 | 42.9 | 2 1/2 | E | 3 | 2.75 |
| 0.546 | 13.9 | 1.714 | 43.5 | 2 3/4 | E 1/2 | ||
| 0.554 | 14.1 | 1.740 | 44.2 | 3 | F | 4 | 4.00 |
| 0.562 | 14.3 | 1.765 | 44.8 | 3 1/4 | F 1/2 | 5 | 5.25 |
| 0.570 | 14.5 | 1.790 | 45.5 | 3 1/2 | G | ||
| 0.578 | 14.7 | 1.815 | 46.1 | 3 3/4 | G 1/2 | 6 | 6.50 |
| 0.586 | 14.9 | 1.840 | 46.7 | 4 | H | 7 | |
| 0.594 | 15.1 | 1.865 | 47.4 | 4 1/4 | H 1/2 | 7.75 | |
| 0.602 | 15.3 | 1.890 | 48.0 | 4 1/2 | I | 8 | |
| 0.610 | 15.5 | 1.915 | 48.7 | 4 3/4 | J | 9.00 | |
| 0.618 | 15.7 | 1.941 | 49.3 | 5 | J 1/2 | 9 | |
| 0.626 | 15.9 | 1.966 | 49.9 | 5 1/4 | K | 10.00 | |
| 0.634 | 16.1 | 1.991 | 50.6 | 5 1/2 | K 1/2 | 10 | |
| 0.642 | 16.3 | 2.016 | 51.2 | 5 3/4 | L | 11.75 | |
| 0.650 | 16.5 | 2.041 | 51.8 | 6 | L 1/2 | 11 | 12.75 |
| 0.658 | 16.7 | 2.066 | 52.5 | 6 1/4 | M | 12 | |
| 0.666 | 16.9 | 2.091 | 53.1 | 6 1/2 | M 1/2 | 13 | 14.00 |
| 0.674 | 17.1 | 2.116 | 53.8 | 6 3/4 | N | ||
| 0.682 | 17.3 | 2.141 | 54.4 | 7 | N 1/2 | 14 | 15.25 |
| 0.690 | 17.5 | 2.167 | 55.0 | 7 1/4 | O | ||
| 0.698 | 17.7 | 2.192 | 55.7 | 7 1/2 | O 1/2 | 15 | 16.50 |
| 0.706 | 17.9 | 2.217 | 56.3 | 7 3/4 | P | ||
| 0.714 | 18.1 | 2.242 | 56.9 | 8 | P 1/2 | 16 | 17.75 |
| 0.722 | 18.3 | 2.267 | 57.6 | 8 1/4 | Q | ||
| 0.730 | 18.5 | 2.292 | 58.2 | 8 1/2 | Q 1/2 | 17 | |
| 0.738 | 18.7 | 2.317 | 58.9 | 8 3/4 | R | 19 | |
| 0.746 | 18.9 | 2.342 | 59.5 | 9 | R 1/2 | 18 | |
| 0.754 | 19.2 | 2.368 | 60.1 | 9 1/4 | S | 20.25 | |
| 0.762 | 19.4 | 2.393 | 60.8 | 9 1/2 | S 1/2 | 19 | |
| 0.770 | 19.6 | 2.418 | 61.4 | 9 3/4 | T | 21.5 | |
| 0.778 | 19.8 | 2.443 | 62.1 | 10 | T 1/2 | 20 | |
| 0.786 | 20.0 | 2.468 | 62.7 | 10 1/4 | U | 21 | |
| 0.794 | 20.2 | 2.493 | 63.3 | 10 1/2 | U 1/2 | 22 | 22.75 |
| 0.802 | 20.4 | 2.518 | 64.0 | 10 3/4 | V | ||
| 0.810 | 20.6 | 2.543 | 64.6 | 11 | V 1/2 | 23 | |
| 0.818 | 20.8 | 2.569 | 65.2 | 11 1/4 | W | 25 | |
| 0.826 | 21.0 | 2.594 | 65.9 | 11 1/2 | W 1/2 | 24 | |
| 0.834 | 21.2 | 2.619 | 66.5 | 11 3/4 | X | ||
| 0.842 | 21.4 | 2.644 | 67.2 | 12 | X 1/2 | 25 | 27.50 |
| 0.850 | 21.6 | 2.669 | 67.8 | 12 1/4 | Y | ||
| 0.858 | 21.8 | 2.694 | 68.4 | 12 1/2 | Z | 26 | 28.75 |
| 0.866 | 22.0 | 2.719 | 69.1 | 12 3/4 | Z 1/2 | ||
| 0.874 | 22.2 | 2.744 | 69.7 | 13 | 27 | ||
| 0.882 | 22.4 | 2.769 | 70.3 | 13 1/4 | Z1 | ||
| 0.890 | 22.6 | 2.795 | 71.0 | 13 1/2 | |||
| 0.898 | 22.8 | 2.820 | 71.6 | 13 3/4 | Z2 | ||
| 0.906 | 23.0 | 2.845 | 72.3 | 14 | Z3 | ||
| 0.914 | 23.2 | 2.870 | 72.9 | 14 1/4 | |||
| 0.922 | 23.4 | 2.895 | 73.5 | 14 1/2 | Z4 | ||
| 0.930 | 23.6 | 2.920 | 74.2 | 14 3/4 | |||
| 0.938 | 23.8 | 2.945 | 74.8 | 15 | |||
| 0.946 | 24.0 | 2.970 | 75.4 | 15 1/4 | |||
| 0.954 | 24.2 | 2.996 | 76.1 | 15 1/2 | |||
| 0.962 | 24.4 | 3.021 | 76.7 | 15 3/4 | |||
| 0.970 | 24.6 | 3.046 | 77.4 | 16 |