Horse & Equine Calculators

The most accurate tape-measure method uses the heart girth formula: (heart girth × heart girth × body length) ÷ 330 = weight in pounds. Measure heart girth (circumference directly behind the front legs) and body length (point of shoulder to point of buttock) in inches. This formula is accurate to within 3% for most adult horses and is used by equine vets and nutritionists worldwide. Our Horse Weight Calculator performs the calculation instantly and converts to kg.

The average horse gestation period is 340 days (approximately 11 months), though it normally ranges from 320 to 370 days. Thoroughbreds tend to foal slightly earlier (330–335 days) while draught breeds and some ponies often go longer (340–355 days). Fillies are sometimes born a few days earlier than colts. Season also plays a role — mares bred in late spring often have shorter gestation than those bred in winter. Our Mare Gestation Calculator accounts for breed differences to give a more precise expected foaling date range.

A horse should consume 1.5–3% of its body weight in forage daily. For a 1,000 lb (450 kg) horse, that means 15–30 lbs (7–14 kg) of hay or combined hay and pasture every day. Easy keepers and horses on lush pasture need the lower end; horses in moderate to heavy work need the upper end. Hay quality matters too — high-quality timothy-alfalfa mix delivers more calories per pound than poor-quality grass hay. Our Horse Feeding Calculator gives exact amounts by body weight, workload level, and hay type.

The Henneke Body Condition Score (BCS) is the standard method used by vets and equine nutritionists. A score of 5 (moderate) is ideal for most horses — you should be able to feel but not easily see the ribs, and the neck and withers should be smoothly muscled without excess fat. Scores below 4 indicate underweight; above 7 indicates overweight. Our Horse Body Condition Score calculator walks you through each of the six areas to assess and gives you an accurate BCS plus feeding adjustments to reach an ideal score.

The widely accepted guideline is that a horse should carry no more than 20% of its own body weight, including the rider and all tack. For a 1,000 lb (450 kg) horse that means a maximum of 200 lbs (90 kg) of rider plus saddle, bridle, and pads combined. Horses with heavier bone structure and draft or warmblood builds can sometimes carry up to 25%, while fine-boned breeds should stay closer to 15–18%. Our Rider Weight Limit Calculator factors in horse weight, breed type, and fitness level for a precise recommendation.

Modern deworming recommendations have shifted from calendar-based rotation to targeted selective treatment based on fecal egg counts (FEC). Horses are classified as low shedders (<200 eggs per gram), moderate shedders (200–500 epg), or high shedders (>500 epg). Low shedders typically need deworming once or twice a year; high shedders may need three to four treatments. At minimum, all horses should receive a boticide (ivermectin or moxidectin) in autumn and a tapeworm treatment annually. Correct dosing by body weight is critical — underdosing drives resistance. Our Horse Deworming Calculator gives you the right dose for your horse’s exact weight.

Annual horse ownership costs vary widely by region and care setup but typically range from $3,000–$10,000+ in the US for a horse kept at home, or $7,000–$20,000+ for full board at a commercial facility. The main cost categories are: boarding or land/stable costs (largest single expense), feed and hay, farrier visits every 6–8 weeks ($50–$200 per visit), routine veterinary care including vaccinations and dentistry, and equipment. Our Horse Ownership Cost Calculator lets you enter your exact local costs to get a personalised monthly and annual breakdown.

As a general guideline, a horse needs a minimum of 1–2 acres of pasture to meet a significant portion of its dietary needs, assuming good-quality grass and rotational grazing management. In practice, the amount required depends heavily on pasture quality, stocking density, rainfall, and how much supplemental hay you feed. In dry climates or heavily stocked paddocks, you may need 3–5 acres per horse to sustain decent grass cover. Our Pasture Size Calculator accounts for all these variables to give you a more accurate acreage estimate for your specific conditions.