Estimating actual and ideal bodyweight of adult horses

In 2011, we took body measurements on 629 adult horses and ponies at two horse shows in St. Paul, Minnesota (WSCA Champ Show and State 4-H Horse Show). The WCSA Champ Show and the State 4-H Horse Show featured primarily Arabians, ponies and stock-type horses.

In 2014, we took the same measurements on 227 adult draft and warmblood horses at the Scott County Fair Draft Horse Show (Jordan, Minnesota) and the Fall Harvest Horse Show (St. Paul). The Scott County Fair Draft Horse Show was exclusively draft horse teams and the Fall Harvest Horse Show was a Hunter/Jumper show attended by primarily warmblood horses.

In 2015, we measured 56 saddle horses at the Friends of the American Saddle Horse (FASH) spring show in St. Paul, MN. We measured 15 additional horses at a private farm in New Prague, MN and 33 additional horses at a private farm in Hugo, MN. We measured 110 gaited horses across four competitive trail riding events in Alabama. A total of 214 saddle-type and gaited horses were measured.

in 2016, we measured 323 horses at the American Miniature Horse Registry (AMHR) Nationals in Tulsa, Oklahoma. There were a large number of horses under the age of three at this show. As a result, there are two groups of miniature horses; 261 adults (three years or older) and 62 juveniles (less than three years old).

In 2017, we measured 88 Thoroughbreds at the New Vocations Charity Thoroughbred Show in Lexington, Kentucky. We also measured 12 Thoroughbreds at the Fall Harvest Horse Show in 2014.

At all shows, we collected data on adult horses that were 3 years old and older and not pregnant. 

Body measurements were taken on all horses. They included: 

• Neck circumference located halfway between the poll and the withers (N). 
• Height at the third thoracic vertebra (H).
• Girth circumference at the third thoracic vertebra (G). 
• Body length from the point of the shoulder to a point perpendicular to the point of the buttock (L).

The following body measurements were taken by trained personnel:

• Body condition score (BCS) on a scale of one (poor) to nine (extremely fat).
• Height at the third thoracic vertebra.
• Neck circumference at the midway point between the poll and the third thoracic vertebra.
• Body length from the point of the shoulder to a line perpendicular to the point of the buttock.
• Girth circumference at the third thoracic vertebra. 

We weighed each horse using a portable livestock scale and recorded age, gender, breed and discipline. For draft horses only, we measured shoe height and used actual height (height minus shoes) in the calculations.

At 2014 and later shows, we asked the exhibitors to estimate their horse's bodyweight prior to weighing horses on the livestock scale. We later compared these bodyweight estimates to actual bodyweight.

Body measurements differed between breed-types. Ponies and draft horses had higher body condition score and Thoroughbreds and warmbloods had lower BCS compared to the other breed types.

Out of the horses we measured, these were considered overweight with a BCS greater than or equal to seven:

• 42 percent of draft horses
• 14 percent of stock horses, ponies and Arabians
• 2 percent of warmbloods

• 20 percent of adult and 2 percent of juvenile miniature horses

• 36 percent of saddle-type horses, which includes gaited horses

When estimating ideal bodyweight for each horse and subtracted from the scale bodyweight, the difference in weight between each BCS averaged:

• 33 pounds for Arabians
• 86 pounds for draft horses
• 18 pounds for adult Miniature horses
• 7 pounds for juvenile Miniature horses
• 22 pounds for ponies
• 33 for saddle-type horses
• 37 pounds for stock horses

• 57 pounds for Thoroughbreds

• 37 pounds for warmbloods

The table below shows body condition score (BCS), average age, body measurements (in inches) and weight (in pounds) of different breed types of adult horses included in this study. Total = number of horses in each group.

Estimating actual bodyweight

(Weight in pounds; girth, length, height, neck in inches)

Arabians, stock horses and ponies

Bodyweight = [girth ^1.486 x length ^0.554 x height ^0.599 x neck ^0.173] / X

X = 119 (Arabians); 119 (ponies); 114 (stock horses)

Draft horses and warmbloods

Bodyweight = 25.09 x [girth ^1.528 x length ^0.574 x height ^0.246 x neck ^0.261] / X

X = 1,181 (draft horses); 1,209 (warmbloods)

Miniature Horse (three years or older) (Wither height less than 34 inches)

Actual weight = 30.419396 x (girth ^1.835632 x length ^0.562047 x height ^0.318683 x neck ^0.0991582)/4,329

Miniature Horse (less than three years old) (Wither height less than 34 inches)

Actual weight = 33.687348 x (girth ^1.637324 x length ^0.437474 x height ^0.701713 x neck ^0.148477)/6,534

Saddle Horse

Actual weight = 26.057987 x (girth ^1.600007 x length ^0.544919 x height ^0.282744 x neck ^0.221832)/1,559

Thoroughbred

Actual weight = ((girth x 27.15628) + (neck x 9.210477) + (length x 8.505886)) – 1790.68

Estimating ideal bodyweight 

(Weight in pounds, height and length in inches)

Arabians, stock horses and ponies

Ideal weight (lbs) = [(15.58 x height) + (23.52 x body length) - X]

X = 1,344 (Arabians); 1,269 (stock horses);  1,333 (ponies)

Draft horses and warmbloods

Ideal weight (lbs) = [(27.55 x height (in)) + (25.98 x body length (in)) - X]

X = 2,092 (draft horses);  2,235 (warmbloods)

Miniature horse (three years or older) (Wither height less than 34 inches)

Ideal weight = 23.248585 x (length ^0.78635 x height ^1.74077)/868

Miniature horse (less than three years old) (Wither height less than 34 inches)

Ideal weight = 33.915120 x (length ^1.91873 x height ^1.26055)/18,209

Saddle horse

Ideal weight = 20.342946 x (length ^1.370407 x height ^1.013487)/359

Thoroughbred

Ideal weight = ((length x 10.69073808) + (height x 23.75553796)) - 1073.380132