How to use the dog water intake calculator
- Enter your dog’s weight.
- To check your dog’s drinking, measure it for 24 hours: fill the bowl with a known amount, top up with measured amounts, and measure what is left the next day. Include all water bowls in the house.
- Read the usual range and whether your measurement is in it.
The formula
Usual range = 20 to 70 ml per kg of body weight per day, from a UK veterinary referral practice’s fact sheet on polydipsia.
Too much = more than 100 ml per kg per day. This is the standard definition of polydipsia used by vets (VIN, “Approach to Polyuria and Polydipsia in the Dog”).
The popular “1 fl oz per lb per day” rule equals about 65 ml/kg, so it sits inside the usual range.
Conversions: 1 US fl oz = 29.57 ml, and 1 cup = 8 fl oz.
Tips
- Fresh water all the time. Dogs should always have clean water available.
- Food makes a difference. Wet food is mostly water, so dogs eating it drink less from the bowl.
- Tummy upsets. Dogs with diarrhoea lose water. Watch drinking alongside a bland diet such as chicken and rice.
- Bring numbers to the vet. A measured 24-hour amount is much more useful than “drinking a lot”.
Sources
- UK veterinary referral fact sheet: Polydipsia in Dogs and Cats (vetspecialists.co.uk): normal 20–70 ml/kg/day; increased over 100 ml/kg/day.
- VIN: Approach to Polyuria and Polydipsia in the Dog: polydipsia defined as more than 100 ml/kg/day.
Frequently asked questions
How much water should a dog drink a day?
Usually about 20–70 ml per kg of body weight a day, according to a UK veterinary referral fact sheet on increased drinking. For a 30 lb (13.6 kg) dog that is roughly 9–32 fl oz (270–950 ml). Hot weather, exercise and dry food all push it up. The popular “1 fl oz per lb” rule (about 65 ml/kg) sits near the top of that range.
How much water should a dog drink in 24 hours?
The same daily range of about 20–70 ml per kg. To check, measure everything you put in the bowls over 24 hours and subtract what is left. More than 100 ml per kg in 24 hours is called polydipsia and is a reason to see your vet: for a 30 lb dog that is over about 46 fl oz (1.4 L).
How much water should a cat drink a day in ml?
Cats drink much less than dogs. Royal Canin’s vet academy cites a typical recommendation of about 50 ml per kg a day, roughly 200–250 ml for an average cat, and Cornell’s Feline Health Center says about 4 oz per 5 lb of lean body weight, counting the water in food. Wet food supplies much of it.
How much water should a dog drink after surgery?
Follow your vet’s discharge instructions, because some procedures need water limited at first. In general a dog should start drinking normally again within a day or so; call your vet if it refuses water or vomits after drinking.
Why is my dog drinking so much water?
Heat, exercise, a salty treat or a switch to dry food can all make a dog drink more for a day or two. Steady heavy drinking, especially with more urination, accidents in the house or weight loss, needs a vet check. Over 100 ml/kg a day can point to diabetes, kidney disease, Cushing’s disease or infection.