One of the common ways to measure a horse is to use a weight tape. You place a tape around the horse’s girth, from just behind the front legs to the back just back of the withers, and on around to where you started. Using the Purina or other weight tape, you will find that the amount of tape required to go around the horse is a pretty accurate measure of the weight of the horse.
Purina research created the weight tape, using a series of overlapping ‘blocks’ that are marked in a sequence of various weights. A measurement of a horse will fall on two staggered blocks, each with a different weight. The weight of the horse is then the average of the weights in the two blocks.
My Purina tape ran from 80 pounds to 1320. Well, I noticed that each block was a bit more difference in weight from the previous weight, and started extrapolating for the next couple of blocks. I found a regular, predictable pattern. The result is the table you see below.
I use a flat nylon longeline to wrap around the heart girth and mark the circumference on the line (I hold my thumbnail at the place the lines meet). Then I measure from the end of the line to the mark (thumbnail) using a tape measure. Then I spot that heart girth measurement on the table below. The reason for the two-step measure is that Kat doesn’t like the rattling noises from the tape measure, and I don’t like fooling with her and the metal rule.
In 1997 I used the tape & chart to estimate my then 3 yo Belgian mare at 1710 pounds, then weighed her on a scale, and came within 10 pounds.
Inches of Heart Girth | Size of Weight Block | Weight of the Block |
29 7/16 | 1 1/2 | 80 |
30 1/2 | 1 1/16 | 90 |
31 5/8 | 1 1/8 | 100 |
32 5/8 | 1 | 110 |
33 5/8 | 1 | 120 |
34 14/16 | 1 1/4 | 135 |
36 1/8 | 1 1/4 | 150 |
37 1/4 | 1 1/8 | 165 |
38 1/2 | 1 1/4 | 180 |
39 3/4 | 1 1/4 | 200 |
41 3/16 | 1 7/16 | 220 |
42 09/16 | 1 7/16 | 245 |
43 15/16 | 1 3/8 | 270 |
45 1/4 | 1 3/8 | 295 |
46 1/2 | 1 1/4 | 320 |
48 | 1 1/2 | 350 |
49 3/8 | 1 3/8 | 380 |
50 11/16 | 1 5/16 | 410 |
52 3/8 | 1 11/16 | 440 |
54 1/16 | 1 11/16 | 475 |
54 15/16 | 0 14/16 | 510 |
56 3/4 | 1 13/16 | 550 |
57 3/4 | 1 | 590 |
59 | 1 1/4 | 630 |
60 1/2 | 1 1/2 | 670 |
61 15/16 | 1 1/2 | 715 |
63 3/8 | 1 7/16 | 760 |
64 3/4 | 1 7/16 | 810 |
66 5/16 | 1 09/16 | 860 |
67 14/16 | 1 09/16 | 910 |
69 5/16 | 1 7/16 | 960 |
70 3/4 | 1 7/16 | 1015 |
72 1/4 | 1 1/2 | 1070 |
73 11/16 | 1 1/2 | 1130 |
75 1/4 | 1 09/16 | 1190 |
76 3/4 | 1 09/16 | 1250 |
78 1/4 | 1 1/2 | 1310 |
79 3/4 | 1 1/2 | 1375 |
81 1/4 | 1 1/2 | 1445 |
82 3/4 | 1 1/2 | 1515 |
84 1/4 | 1 1/2 | 1590 |
85 3/4 | 1 1/2 | 1665 |
87 1/4 | 1 1/2 | 1745 |
88 3/4 | 1 1/2 | 1830 |
90 1/4 | 1 1/2 | 1920 |
91 3/4 | 1 1/2 | 2010 |
93 1/4 | 1 1/2 | 2105 |
94 3/4 | 1 1/2 | 2200 |
96 1/4 | 1 1/2 | 2300 |
For example, I just measured Kat as 87 3/4″ girth. The two blocks are 1745 and 1830 pounds, the average (Kat’s weight) is 1787 pounds, +/- 50 pounds.
I use this table — have fun with it!.