Wednesday, January 2, 2008

How big will a foal or young horse get?

When I was looking to buy a weanling, I lusted after this lovely weanling in Riegelsville, PA (pictured left). He was a big boy at birth and large for his age when I was considering him. He was out of my price range, and the gods were smiling on me because now as a long yearling, it's looking like he will probably top out at 16.1 or 16.2. As a tall person (5 foot 10 inches) w/a 36" inseam, a tall horse is pretty much a necessity if I don't want my feet to drag on the ground!

There's not a heap of scholarly research on predicting horse height, at least not in the licensed databases I can access. So, I found what I could on the Internet - veterinary journals, forums, advice columns. I also talked to breeders, who gave candid evaluations of the likely mature height of horses I looked at. Below is a summary of the collected wisdom and the actual source info...


  • a mare's first foal tends to be born smaller than subsequent foals, and the first baby's mature height is slightly smaller.
  • some claim that height is inherited more from the dam.
  • look at sibling height to help predict mature height, esp any full siblings.
  • look at height of parents through great-grand parents.
  • Find out the dam and sire's reputation for "throwing size."
  • overfeeding will speed up growth but will not affect final height.
  1. MOST ACCURATE is to measure elbow to ergot/fetlock with a string. Then "flip" the string, rotating from the elbow and raising the bottom part of the string up, vertical and taut, aligned with the wither. This is the final horse height.
  2. Second string test method: measure from the front part of the coronet band on the hoof right where the hoofwall meets hair, and pull a string straight up to the center of the horses knee (where the dip is in the middle of the joint). That measurement will co-incide with the horses final height. So if the measurement is 15 and 3/4 inches, the horse will be 15'3.
  3. Evaluate your youngster's general conformation as a yearling or later. Is he or she extremely lanky/gawky, or are the proportions more similar to an adult/mature horse. If it is the latter, your horse may not grow much more.
  4. Rough guesstimate at one year, take current height and add two hands.
  5. The cannon bone has reached its full length at one year old, and it is about 98% its full length at birth. Compare a baby's knee height to its mom, or to others its age, or to other broodmares. Find an adult whose knees are roughly the same distance from the ground, the baby/youngster is likely to end up the same or similar height.
  6. There are percentage growth estimates:

  Age in Months  Percent of Mature Height

          Birth              61 to 64

            1                67 to 70

            3                76 to 79

            6                83 to 86

            9                87 to 90

           12                90 to 92

           18                94 to 96

           24                96 to 98

           30                97 to 99

           36                98 to 100

           48                99 to 100

           60                100

For draft horses the estimates are different, reflecting slower growth...

   Age in months          Percent mature height
        6                           79
       12                           89
       18                           92


Equine Chronicle article: Growth rates in foals
String Testing
Visual aids for string tests!!!

Horse Advice on weanling height
This Web site has some free information and an article available for a fee. I found that the info from the fee based article is available freely on the Internet.

Today's Horse
Great, sensible advice from Dr. Jessica Jahiel about predicting height.

Horse Express
This includes growth percentage charts for various breeds, and the reader might be able to guesstimate a particular breed (e.g., warmbloods) based on these charts.

Skeletal growth rates of weanling and yearling thoroughbred horses
This is an interesting, if detailed article that discusses growth rates and weight for yearling thoroughbreds, bone by bone.

Estimation of Heritabilities for Weight, Height and Front Cannon Bone Circumference of Thoroughbreds
Discusses heritability of height. 

Horse Spine Growth
Basically a tidbit about the growth rate of the spine, which continues after full height is achieved.
I'm unfamiliar with the site's author/editor, but it offered some interesting casual tidbits so I'm including it.



  1. Hello, this is an awesome blog! I, too, am 5' 10" and don't want to buy an weanling and find "my feet" dragging on the ground! Looking at PMU foals, which are part draft crosses, so thanks much for the info that it takes longer for them to "fully mature." Gonna be a little while for me to buy a couple of foals -- housing market tankeed -- go figure.

    Anyhow. I am looking for an Endurance Horse, so don't give care about pedigree, only care about conformation, light head, strong shoulders (for going down on inclines!) and a good mover that has a smoot trot, belive it or not, most of Endurance is at a fast walk, trot, or extended trot, gallop only at the very end. So, unless you get a foal that has a "smooth" gait from the git-go, asa well as being tall, well, I feel like I am rolling the dice either way, going to buy two and train them the same with and older gelding.

    Hope one turns out to be top player!


    Miss Faith Claire
    Lacey, WA

  2. Ok, these guys have nothing to worry about. I am over 6' 2" and ride a very thin athletic appaloosa horse that is only 14.3h tall. He carries me just fine, i even barrel race him. Just becuase you may look a little funny there is no reason to shy away from a small horse. You may get laughed at, but when you clean up at an event it won't take long to get respect. Great blog though. Alex L.

  3. lol, i guess it is funny to you guys that i have the opposite problm.
    i am 5' nothing.
    everyone else seems to think it is hilarious watching me get onboard. anything over 15.2 has the stirrup roughly level with my shoulder, and me trying to work out how to get my foot up there.:P but i manage. (i have ridden up to 16.3, and built like a tank to boot)
    all just encouragement to build a good "stand", and to NOT fall off, cos its a mongrel trying to get back on without a block!

  4. It's funny, our proportions are exact, I'm also 5'10" and a 36" inseam, and I'm looking at a 3yo thoroughbred filly to buy that I'm hoping will end up over 17h but reading this has made me question it a little. Thank you for this information and I too hate the word "analyzation". :) Normalcy gets me too.. What ever happened to the word normality? :) Again, thanks for the information and take care. -Kirby

  5. Нмм, so my 6 monts old male colt is 130 cm. in Your table about 6 month it say it is 83 to 86% from his final height. What will be his final height acording to this? Sorry, i'm not good in math :(

    1. You will take 130 ÷ .86 which will give you 151 cm. That is only an estimation however.

    2. You will take 130 ÷ .86 which will give you 151 cm. That is only an estimation however.


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