Horse Weight & Body-Condition Calculator
Use two tape measurements for a weight estimate. Add the body-condition score you assessed by hand to understand the result and when to call your veterinarian.
Your horse's estimated weight
For a healthy, mature horse in suitable condition only. This is not a ration or an individual minimum. Pasture counts toward forage; dry matter excludes water, so these are not pounds of hay or fresh grass as fed. Forage quality, workload and health change actual needs.
A starting point, not veterinary advice. A selected condition score is not a diagnosis. Use a veterinarian or equine nutritionist for feeding plans; this tool does not set a target weight, medication dose or ration.
Sources & methodology
With the horse standing square, measure heart girth around the barrel behind the withers and elbow. Measure body length from the point of shoulder to the bony point of the buttock (ischial tuberosity). Use inches and a consistent technique.
Estimated weight (lb) = heart girth² × body length ÷ divisor
- Merck Veterinary Manual lists divisors of 330 for horses over two years, 301 for yearlings and 280 for weanlings. Kilograms are pounds × 0.453592.
- The pony divisor of 299 comes from North Wind Equine's veterinary-practice guidance. Its validation evidence is less established; do not assume equal accuracy across pony breeds or conditions.
- Neither a formula nor a weight tape guarantees a fixed error range. Carroll and Huntington's body-weight research supports using body measurements, but does not establish a universal percentage-accuracy promise. Use a calibrated livestock scale when precision matters.
- Wagner and Tyler’s adult-horse study (PDF) found that the shoulder-to-buttock measurement outperformed the tested weight tape in that sample. It excluded pony breeds and horses under two, and does not establish accuracy for every horse or tape.
- Merck distinguishes forage intake (1.5–2% of body weight as dry matter) from the average maximum total daily dry-matter intake, usually 2–2.5%. The result's multiplication is an illustration for healthy mature horses with a selected score of 4–6, not a complete diet. It is withheld for unknown scores, growing horses, thin horses and scores 7–9. Dry matter excludes water; hay as fed weighs more, and pasture moisture varies.
- University of Minnesota Extension explains condition assessment and individual weight management. A score does not determine a target weight or a timetable here.
- For severe thinness or possible starvation, Witham and Stull's refeeding study and the UC Davis refeeding report (PDF) support veterinary supervision because metabolic complications can occur.
- UC Davis guidance on equine metabolic syndrome requires attention to soundness: horses with active laminitis should not exercise.
Evidence checked October 18, 2026. The 20–120 inch input limits catch entry errors; they do not certify the formula for every animal within those limits. This tool does not assess illness, pregnancy, workload, feed analysis or recent starvation.
The Henneke body-condition score (1–9)
Assess fat cover at the neck, withers, behind the shoulder, ribs, loin and tailhead, by sight and touch. A heavy coat can hide the outline. The score describes fat, not muscle. You select the score; the calculator cannot infer it from measurements.
| Score | Condition | Context |
|---|---|---|
| 1–2 | Poor / very thin | Prominent bones and very little fat. Seek prompt veterinary assessment and supervised refeeding evaluation; routine weight-gain advice is inappropriate. |
| 3 | Thin | Visible ribs and limited fat cover. Investigate the cause with your veterinarian. Suspected starvation needs supervised refeeding, regardless of score. |
| 4 | Moderately thin | Faint rib outlines; may suit some working horses. Consider workload, health and the trend before changing feed. |
| 5 | Moderate | Ribs easily felt, a level back, and neck and shoulder blending smoothly into the body. |
| 6 | Moderately fleshy | More fat cover; can be appropriate for some horses. A score alone does not require weight loss. |
| 7–9 | Fleshy to extremely fat | Discuss weight and metabolic risk with your veterinarian. Avoid abrupt feed restriction. No exercise during active laminitis; obtain veterinary soundness clearance first. |
Common horse weight questions
How do you calculate a horse's weight without a scale?
Measure heart girth and body length in inches. Estimated weight in pounds = heart girth squared × body length ÷ divisor. Use 330 for horses over two years, 301 for yearlings and 280 for weanlings. The pony option uses 299, a veterinary-practice rule with less validation evidence. These are estimates, not scale weights.
How accurate is the horse weight formula?
Accuracy varies with breed, age, condition, conformation and measurement technique. There is no guaranteed percentage error for an individual horse. Use a calibrated livestock scale when accuracy matters, and ask your veterinarian about weight-sensitive medication decisions.
Is a weight tape accurate for horses?
A weight tape estimates weight from girth. Girth-and-length equations can perform better in some studied populations, but neither method is consistently best for every horse. Use the same method and measuring technique to monitor trends; use a scale to check actual weight.
What is a good body condition score for a horse?
A Henneke score of 5 describes moderate condition. Scores 4–6 can be appropriate depending on the individual horse, workload and life stage; a 4 or 6 does not automatically mean weight gain or loss is needed. Ask your veterinarian to help set an individual goal.
Where do you check a horse's body condition?
Assess fat cover by sight and touch at the neck, withers, behind the shoulder, ribs, loin and tailhead. A heavy coat can obscure the view. This score describes fat cover, not muscle, and cannot be calculated from two tape measurements.
What if my horse is very thin or may have been starved?
A score of 1–2, or suspected starvation at any score, needs prompt veterinary evaluation and a supervised refeeding plan. Refeeding can cause serious metabolic complications. Do not use routine forage amounts or weight-building feed advice from a calculator for this situation.
