Horse Calculators
Equine calculators: weight (heart girth method), pregnancy (340-day), feed, dewormer and hay.
- Horse Weight CalculatorEstimate horse weight using the heart-girth × body-length formula. Covers adults, foals, yearlings, ponies and draft horses.weightOpen
- Horse Pregnancy CalculatorCalculate your mare's foaling date with a breed-adjusted gestation (Thoroughbred 340d, Draft 345d). Trimester care calendar.pregnancyOpen
- Horse Feed CalculatorCalculate daily hay and grain for your horse based on weight, activity level and feed type. 2 % rule plus workload adjustments.feedingOpen
- Horse Dewormer Dosage CalculatorCalculate the correct dewormer dose for horses by bodyweight. Supports ivermectin, moxidectin, fenbendazole and combination tube wormers.dosageOpen
- Horse Blanket Size CalculatorCalculate your horse's blanket size. Standard US sizing = center of chest to point of buttock (inches), in 3-inch increments.equipmentOpen
- Horse Bit Size CalculatorFind the correct bit size by measuring mouth width. Covers snaffles, Western bits, pony bits — standard US bit sizes in 1/4 inch increments.equipmentOpen
- Horse Age by TeethEstimate a horse's age by teeth — Galvayne's groove, cup wear, slope of incisors. Based on equine dental aging literature.ageOpen
- Thoroughbred FeedFeed calculator for Thoroughbred racehorses in training. Higher grain (2-3 lb per 100 lb BW) + quality forage + electrolyte support.breedfeedingOpen
About horses in the United States
There are approximately 6.6 million horses in the United States, including leisure horses, working horses, sport horses and pasture pets. Horse care involves very different math than dog or cat care — pregnancy is ~340 days, daily feed is 2% of body weight (so 20+ lb for adults), and equipment sizing (bit, blanket, saddle) requires precise measurements.
What horse tools do most owners need?
Weight calculator (for deworming and feed math — vital since horses are rarely weighed), hay calculator (winter planning), pregnancy calculator (breed-adjusted gestation), and equipment sizing (bit, blanket).
Horse calculator FAQ
How do you weigh a horse without a scale?
Heart-girth × body-length formula: weight (lb) = (HG² × BL) / 330 for adults. Accuracy ±5–10%. Weight tape less accurate but faster. Details in our Horse Weight Calculator.
How long is a horse pregnant?
340 days average for the common breeds (range 320–370). Thoroughbreds slightly shorter, drafts slightly longer. See our Horse Pregnancy Calculator.
How accurate are these calculator results?
Our calculators implement the exact formulas used in veterinary textbooks, AAFCO/NRC nutrition standards, AAHA/AAFP life-stage guidelines, and peer-reviewed research. Results are accurate within the precision of the input data. For medical decisions (toxicity, drug dosing, diabetic insulin), always confirm with your veterinarian — calculators are educational tools, not clinical devices.