Dog Food Calculator
Work out how much to feed your dog each day in calories and cups, based on weight, age, neuter status and activity level. Free, no signup.
How the calculation works
Every figure above comes from two steps that veterinary nutritionists use in exactly this order. Nothing here is proprietary — you can check the arithmetic yourself, and the "show the working" line under each result prints the numbers that went in.
Step 1 — Resting energy requirement (RER)
This is what a dog burns at rest: awake, digesting, but doing nothing. It does not scale in a straight line with body weight, which is why a dog twice as heavy does not need twice the food. The relationship follows metabolic body size:
RER (kcal/day) = 70 × (body weight in kg)^0.75A 20 kg (44 lb) dog therefore has an RER of about 662 kcal — not the 1,400 that a naive doubling from a 10 kg dog would suggest.
Step 2 — Multiply by the life-stage and activity factor
RER is then multiplied to give the maintenance energy requirement (MER), the realistic daily total for a dog that walks, plays and grows. The multiplier is where life stage, neuter status and workload enter:
| Situation | × RER |
|---|---|
| Puppy, under 4 months | 3.0 |
| Puppy, 4–12 months | 2.0 |
| Neutered adult | 1.6 |
| Intact adult | 1.8 |
| Senior, less active | 1.2–1.4 |
| Weight loss (on ideal weight) | 1.0 |
| Active / working dog | 2.0–5.0 |
Neutering genuinely lowers the requirement — roughly 20–30% — which is why so many dogs quietly gain weight in the year after the operation while their bowl stays exactly as full as before.
Why weight loss uses a different starting weight
For a dog that needs to slim down, the calculator asks for a target weight and runs the whole calculation from that figure instead. Basing a diet on the current weight simply maintains the current weight more slowly. A safe rate is 1–2% of body weight per week; anything faster tends to strip muscle alongside fat, and in an overweight dog muscle is the thing you least want to lose. Ask your vet to set the target — a realistic goal is often an interim figure rather than the textbook breed weight.
Turning calories into cups
Calories are the real unit; cups are just how the food gets into the bowl. Divide the daily target by the kcal-per-cup figure on your bag and you have the volume. Two cautions: a "cup" means a standard 8 fl oz measuring cup, not whatever mug lives in the bin of kibble, and the same food can change density between formulations, so re-check the number when you switch bags. If you feed wet food, or wet and dry together, work in calories throughout and split the target between the two by whatever proportion you prefer. Our guide to reading a dog food label covers where each of these numbers hides on the packaging.
Checking the result against the actual dog
A calculator cannot see your dog; your hands can. Run them along the ribcage — you should feel the ribs easily under a thin layer of covering, without pressing. Seen from above there should be a visible waist behind the ribs, and from the side the belly should tuck up rather than run level. If the ribs are hard to find, the ration is too generous no matter what any formula says. If they are sharp and the hips protrude, it is too small. Recheck every two to three weeks and adjust by around 10% at a time; if your dog is carrying extra weight, that guide walks through the whole process.
Common questions
- How many cups of food should I feed my dog per day?
- There is no single cup figure that works for all dogs, because cups are a measure of volume and dogs need energy. A cup of dense, high-fat kibble can carry 500 kcal while a cup of a light weight-management formula carries barely 280 — feeding "two cups" of each delivers wildly different amounts. Work out the daily calorie target first, then divide by the kcal-per-cup printed on your specific bag. That is exactly what this calculator does.
- Should I feed my dog once or twice a day?
- Two meals a day suits most adult dogs: it keeps hunger steadier and spreads the digestive load. Puppies under six months generally need three or four smaller meals because they cannot hold enough at once to meet their energy needs. Large and giant deep-chested breeds should never be fed one big meal, as a single large volume is associated with a higher risk of bloat (gastric dilatation-volvulus). Splitting the daily total does not change the total — only how it arrives.
- Why does the calculator ask for a target weight when my dog needs to lose weight?
- Because feeding a smaller ration of what an overweight dog currently eats tends to stall. Veterinary weight-loss plans base the ration on the dog's *ideal* weight, not its current one, then feed at roughly the resting energy requirement for that ideal figure. That gives a genuine energy deficit while still covering maintenance needs. Aim for 1–2% of body weight lost per week; faster than that risks losing muscle rather than fat.
- Do treats count toward the daily total?
- Yes, and they are the single most common reason a carefully measured diet stops working. Treats, dental chews, training rewards and table scraps should stay under 10% of the daily calorie target — the remaining 90% comes from complete food, which is what carries the balanced vitamins and minerals. A couple of large biscuits can quietly use up a small dog's entire treat allowance for the day.
- How accurate is this calculator?
- The formula is the one veterinary nutritionists use as a starting point, but it describes a population average, and individual dogs vary by roughly ±20% around it. Two dogs of the same weight, age and neuter status can genuinely need noticeably different amounts. Treat the result as an opening ration: feed it for two to three weeks, weigh your dog, and adjust up or down based on what the scale and your hands over the ribs tell you.