Dog Water Intake Calculator

daily target (mL) = body weight in pounds × 1 fluid ounce, converted to millilitres; textbook low = weight in kg × 20; textbook high = weight in kg × 70; the increased-drinking line = weight in kg × 100; intake per kg = millilitres drunk ÷ weight in kg

weight

The dog's body weight in kilograms. Every line on the page is proportional to it, which is why a small dog and a large one cannot be compared on millilitres alone

intake

How much the dog actually drank in a day, in millilitres, litres, cups or fluid ounces. Measuring it means measuring the bowl rather than guessing from how often the dog visits it

waterTarget

The rule of thumb of one fluid ounce per pound of body weight, converted to millilitres. At 65.2 mL/kg it lands near the top of the textbook range, not in the middle, and both are shown so that the difference is visible

intakePerKg

What the dog drank, divided by its weight and rounded to one decimal place. This is the figure the textbook range and the increased-drinking line are both written in, and it is the one to quote to a vet

The first use is portioning: knowing roughly how much a dog should drink in a day is how you notice when it has changed, and change is the thing that matters. The second is the reason this page exists — increased drinking is one of the earliest signs of kidney disease, diabetes and Cushing's disease in dogs, and it is easy to miss because a dog that drinks more also urinates more, which people notice as an accident rather than as a symptom. Measuring the bowl for a couple of days and dividing by weight turns a vague impression into a number a vet can act on. If the dog is on a wet food diet, remember that canned food is around three quarters water, so a dog eating mostly wet food will drink noticeably less from the bowl and still be perfectly well hydrated.

1. A 20 kg dog that drank 1,000 mL in a day

   1. The rule of thumb: 20 kg is 44.1 lb, and 44.1 fluid ounces is 1,304 mL a day
   2. The textbook range: 20 × 20 = 400 mL at the low end, 20 × 70 = 1,400 mL at the high end
   3. The increased-drinking line: 20 × 100 = 2,000 mL
   4. What the dog actually drank: 1,000 ÷ 20 = 50.0 mL/kg
   5. 50.0 mL/kg is inside the 20 to 70 range, so this dog is drinking normally

   This is the default on the page. Look at the gap between the two targets: 1,304 mL from the rule of thumb against 400 to 1,400 mL from the textbooks. The rule of thumb is not the middle of the range — it is close to the top of it, so a dog drinking 1,300 mL and a dog drinking 700 mL are both inside the range the textbooks give, even though one is at the rule of thumb and the other is half of it.

2. A 30 kg dog that drank 2,500 mL, and the band nothing catches

   1. The rule of thumb: 30 kg is 66.1 lb, which is 1,956 mL a day
   2. The textbook range runs 600 to 2,100 mL, and the increased-drinking line is 3,000 mL
   3. What the dog actually drank: 2,500 ÷ 30 = 83.3 mL/kg
   4. 83.3 is above the 70 mL/kg top of the textbook range but below the 100 mL/kg line
   5. So this dog is above the range and not yet over the line

   This is the band most people have never heard of, and it is the reason the page shows four bands rather than three. A dog at 83.3 mL/kg is drinking more than textbooks describe as normal and less than the 100 mL/kg that counts as definitively increased. Nothing here says the dog is ill, and nothing here says it is fine either. The useful move is to measure it over several days and write the figures down, so that a vet has a trend rather than a single day.

3. A 5 kg dog that drank nothing measurable

   1. The rule of thumb: 5 kg is 11.0 lb, which is 326 mL a day
   2. Textbook range 100 to 350 mL; the increased-drinking line 500 mL
   3. What the dog actually drank: 0 ÷ 5 = 0.0 mL/kg, the bottom band
   4. The other four figures are still shown, so the page is not blank

   Zero is a real input and a useful one, but read it as a measurement before reading it as a symptom. A dog that drinks from a second bowl, a toilet, a puddle or a pond will look like a dog that drank nothing, and a wet food diet can cut bowl drinking by half. Weigh the bowl over 24 hours and check again before treating this as a finding — and if a dog that was drinking normally has genuinely stopped, that is a reason to call a vet today.

Every number on this page is scaled to body weight, and body weight is the input most people estimate rather than measure, so weigh the dog if the answer matters. The textbook range is deliberately the widest one available. Other sources give narrower figures — WSAVA conference material suggests 50 to 60 mL/kg a day, and some veterinary sites give 40 to 60 — and this page uses 20 to 70 because the same source adds that marked variation is seen between individuals. A narrow range would flag a perfectly normal dog as abnormal. Water intake is also not a diagnosis in either direction: drinking more than 100 mL/kg a day is a reason to see a vet, not a disease, and there are common non-medical causes including a dry food diet, hot weather, exercise, and steroid or diuretic medicines. A dog on a wet food diet may drink very little from the bowl and be properly hydrated; a dog with kidney disease may drink a great deal and still be dehydrated. Measuring intake also cannot separate drinking from urination, and the two usually move together. Finally, this page covers dogs only; cats drink far less per kilogram, and the same bands do not transfer.

How much water should a dog drink a day?

Between 20 and 70 mL per kilogram of body weight is the range textbooks give, which for a 20 kg dog is 400 to 1,400 mL. The rule of thumb that circulates most widely is one fluid ounce per pound of body weight, and that works out at 65.2 mL/kg — near the top of the range rather than in the middle, so the two ways of answering the question disagree by a factor of about three at the wide end. Both are shown on this page because both are reproduced widely, and the range is the more defensible answer for a single dog.

How do I tell whether my dog is drinking too much water?

Weigh the bowl. Fill it, measure how much goes in, and measure what is left 24 hours later, then divide the difference by the dog's weight in kilograms — do that for two or three days, because a single day tells you very little. Above 70 mL/kg a day the dog is drinking more than textbooks describe as normal; above 100 mL/kg the intake counts as definitively increased and is worth a vet visit. Watch urination at the same time, since drinking and urinating usually rise together, and note that a dog on wet food will drink much less from the bowl.

What is polydipsia in dogs?

Polydipsia is the medical term for drinking more than normal — the threshold usually quoted is over 100 mL per kilogram of body weight per day, and it is almost always accompanied by polyuria, which is passing more urine. The pair matters because it is one of the earliest signs of several serious conditions in dogs, including kidney disease, diabetes mellitus and Cushing's disease, and because owners tend to notice the accidents indoors before they notice the water bowl going down. It is a reason to see a vet rather than a diagnosis in itself.

Can a dog drink too little water?

Yes, but check the measurement before you worry. Dogs eating mostly wet food take in around three quarters of their water in the food, so they drink far less from the bowl and are perfectly well. Dogs that drink from a second bowl, a pond or a toilet will also look like they drank almost nothing. If a dog that normally drinks has genuinely stopped, and especially if it is also off its food or vomiting, that is a reason to contact a vet the same day rather than to recalculate.

Does the rule of thumb agree with the textbook range?

No, and the gap is the most useful thing on this page. One fluid ounce per pound is 65.2 mL/kg once the units are converted, which sits near the top of the 20 to 70 mL/kg range rather than in the middle of it. That means the popular rule is the more generous of the two, and a dog drinking around half the rule of thumb can still be inside what textbooks call normal. This calculator shows the rule of thumb as the headline figure because it is the one people repeat, and shows the textbook range underneath it so the difference is visible rather than hidden.

• Polydipsia in Dogs and Cats (increased drinking) — Davies Veterinary Specialists
• How Much Water Does a Dog Need? — PetMD (reviewed by Jennifer Larsen, DVM, PhD, DACVN)
• Nutritional Requirements of Small Animals — MSD Veterinary Manual
• Global Nutrition Guidelines — World Small Animal Veterinary Association