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Enter your horse body weight in kilograms, pick the workload from idle to heavy, and pick the climate from cool to hot. The calculator starts from 0.055 litres per kg, about 27.5 litres for a 500 kg horse at rest in mild weather, inside the published 21 to 29 litre idle range, then scales for work and heat. It returns daily water in litres and gallons, a weekly total, and 20 litre buckets per day. These are planning estimates, not veterinary advice, and lactating mares, heavy sweating and illness all push needs higher.
A 500 kg horse at rest in mild weather drinks about 21 to 29 litres a day according to National Research Council figures, and this horse water intake calculator anchors on 27.5 litres, or 0.055 litres per kg, for that case. Workload scales the figure: light work multiplies by 1.3, moderate work by 1.7, and heavy work by 2.4. Climate scales it again: cool by 0.9, mild by 1.0, and hot by 1.8. Worked example: a 500 kg horse in moderate work in mild weather needs 46.75 litres a day, which is 12.35 gallons, 327.25 litres a week, and 2.3 buckets of 20 litres. A second example: the same horse idle in mild weather needs 27.5 litres, which is 7.26 gallons, 192.5 litres a week, and 1.4 buckets. A horse water intake chart built on gallons per 100 lb of body weight tells the same story: about 1 gallon per 100 lb at rest, rising sharply with heat and work.
Idle horses in cool weather sit at the bottom of the range, around 5 to 8 gallons a day for a 1000 lb horse, while the same horse in hot weather can need 11 to 14 gallons at rest and 19 to 24 gallons in moderate exercise at high temperature. Heavy training or competition in hot humid weather can raise needs 300 to 400 percent above maintenance, because horses can lose up to 4 gallons of sweat per hour during intense work. Winter is a hidden risk: horses drink less when water is near freezing, with intake dropping 38 to 41 percent in some studies, which raises impaction colic risk. Water at 50 to 65 degrees Fahrenheit encourages drinking, and heated waterers help in freezing weather.
Sweat is the main cooling system for horses, and it carries away sodium, chloride and potassium, plus smaller amounts of calcium and magnesium. A 1000 lb horse needs about 1 to 2 ounces of plain salt a day at rest, rising to about 6 ounces with exercise in hot weather. Loose salt is usually eaten more readily than salt blocks. Electrolyte supplements help after heavy sweating, but they must always come with free access to water: giving electrolytes to a horse that is not drinking can worsen dehydration. Offer water during and after exercise, not only at the end of the day, and keep plain water available alongside any electrolyte water.
Green pasture can supply much of a horse water need, since lush grass is 65 to 80 percent water, so a horse on good pasture may drink visibly less from troughs without being short of water. Dry hay diets raise drinking, because hay carries almost no moisture, and high protein, high salt or high fibre feeds also raise intake. Water quality matters: horses prefer clean palatable water at 50 to 65 degrees Fahrenheit, and odour, iron, sulphur or algae can cut intake sharply. Clean troughs and buckets regularly, shade them in summer, and test water if intake drops without an obvious cause.
Horse dehydration signs include dullness, loss of skin elasticity, dry gums, reduced urination, and in severe cases weakness or colic signs. A full day of little or no drinking is always a concern, and a horse can only survive about 3 to 6 days without water. Lactating mares need far more water than idle horses, roughly 40 to 63 litres a day for a 500 kg mare, because milk is mostly water. Never restrict water to manage a wet bed or frequent urination, and call a veterinarian promptly for sudden thirst changes, colic signs, or a horse that refuses water while sweating heavily. This page gives estimates, not professional advice.
Most adult horses drink 5 to 15 gallons a day at rest, depending on size, workload and weather. A 500 kg horse at rest in mild weather drinks about 21 to 29 litres, or 5.5 to 7.5 gallons.
About 6 to 10 gallons a day at rest in mild weather, rising to 15 to 20 gallons or more on a hot day with work. The calculator gives a weight based figure in both litres and gallons.
Yes, sharply. The same 500 kg horse goes from about 21 to 29 litres idle at 20 degrees Celsius to about 42 to 54 litres at 30 degrees, and moderate exercise at 30 degrees pushes it to about 72 to 92 litres.
About 1 to 2 ounces of plain salt a day at rest, rising to about 6 ounces with exercise in hot weather. Salt encourages drinking, but always provide free access to water with it.
Electrolytes help replace sodium, chloride and potassium lost in sweat after heavy work, especially in heat. They are not a daily substitute for salt and water, and they must never be given to a horse that is not drinking.
About 50 to 65 degrees Fahrenheit (10 to 18 degrees Celsius). Near freezing water can cut intake by about 38 to 41 percent, which is why heated waterers matter in winter.
Yes. Lush pasture grass is 65 to 80 percent water, so grazing horses can meet much of their need from grass and drink less from troughs. Hay fed horses drink more.
Dullness, dry gums, slow skin tent return, reduced urination, weakness and colic signs. A horse that barely drinks for a full day needs prompt veterinary attention.