About the Pet Water Intake Calculator
This pet water intake calculator estimates how much water your dog or cat needs each day and how much of that it should actually drink from the bowl. Enter your pet’s weight, its activity level and the weather, and whether it eats dry kibble, wet food or a mix. You get total daily water needs, the amount supplied by food, and the amount to expect it to drink in ounces, cups and milliliters.
Healthy dogs need roughly 60 mL of water per kilogram of body weight a day (a little under an ounce per pound) and cats about 50 mL per kilogram. Diet makes a big difference: canned and raw foods are about 75–80% water, so a cat on wet food may drink only a few sips, while the same cat on kibble has to drink almost all of its water.
Use it to set up bowls and fountains, plan water for hikes and car trips, or check whether your pet is drinking much more or less than expected. A sudden, lasting increase in thirst can be an early sign of kidney disease, diabetes or other illness, and a pet that stops drinking needs attention — so if the bowl is emptying unusually fast or not at all, talk to your vet.
With the default inputs, the water to drink per day is 43.7 fl oz. Change any value above to recalculate instantly.
How to use the pet water intake calculator
- 1Choose dog or cat and enter your pet’s weight.
- 2Pick the activity level and weather.
- 3Select the main type of food your pet eats.
- 4Read how much your pet should drink per day in ounces, cups or milliliters.
- 5Compare with what actually disappears from the bowl over a day or two.
Formula and method
Daily water need is estimated from body weight: about 60 mL per kg for dogs and 50 mL per kg for cats, which sits in the middle of the commonly quoted maintenance range of 50–60 mL/kg and is close to the rule of thumb of one millilitre of water per kilocalorie eaten. Very active pets or warm weather raise needs by about 25%, and hard exercise or heat by about 50%.
Part of that water comes from food. Dry kibble is only about 10% moisture and supplies around 5% of daily needs, while canned and raw food (75–80% moisture) supplies about three-quarters; a mixed diet is set at 40%. The rest is what your pet should drink. Ounces are US fluid ounces (29.57 mL) and a cup is 8 fl oz. About 100 mL per kg per day is used as the point at which thirst is considered excessive.
- base mL/kg
- 60 for dogs, 50 for cats
- activity factor
- 1.0 normal, 1.25 active/warm, 1.5 hard exercise/hot
- food share
- Share of water supplied by the diet (5%, 40% or 75%)
Worked examples
50 lb dog on kibble
50 lb is 22.7 kg, so total need is 22.7 × 60 ≈ 1,361 mL. Kibble supplies about 5%, leaving roughly 1,293 mL — about 43.7 fl oz or 5½ cups — to drink.
10 lb cat on wet food
A 10 lb (4.54 kg) cat needs about 4.54 × 50 ≈ 227 mL of water a day. Wet food provides about 75% (170 mL), so the cat only needs to drink around 57 mL — under 2 fl oz.
30 kg dog hiking in hot weather
30 kg × 60 mL = 1,800 mL, and hard exercise in heat adds 50% for 2,700 mL. With kibble providing 5%, the dog should drink about 2,565 mL (about 10.8 cups), so carry plenty.
Frequently asked questions
How much water should a dog drink a day?+
Most healthy dogs need about 50–60 mL per kg of body weight daily — a little under one fluid ounce per pound. A 50 lb dog on dry food typically drinks around 40–50 fl oz (5–6 cups), more when active or hot.
How much water should a cat drink a day?+
Cats need roughly 50 mL of water per kg per day in total — about 200–250 mL for a typical 4–5 kg cat. On dry food most of that must be drunk; on wet food the cat may drink only 50 mL or so.
Is the “1 ounce per pound” rule right for dogs?+
It is a reasonable upper estimate. One fluid ounce per pound is about 65 mL per kg, slightly above typical maintenance needs, and it counts total water — so dogs on wet food drink noticeably less than this.
How much water is too much for a dog?+
Vets generally consider more than about 100 mL per kg per day (roughly 1.5 fl oz per pound) excessive. Persistent heavy drinking can signal kidney disease, diabetes, Cushing’s disease or infection and should be checked.
How can I get my cat to drink more water?+
Feed some wet food, add water to meals, try a circulating fountain, use wide shallow bowls placed away from the food and litter box, and keep water fresh. Many cats prefer running water.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.