How much should you actually be feeding?

Where these numbers come from

This calculator starts from resting energy requirement (RER = 70 × body weight in kg^0.75) — the standard veterinary starting point for how much energy an animal burns at rest — then multiplies it by factors for life stage (growth, adult, senior), breed size, activity level, neutering status and body condition. The result in calories is converted to grams using the energy density (kcal per kg) of the food you pick below.

Where a product's energy density is a published, lab-confirmed figure, the result shown next to it will say so; figures marked as estimates are calculated from the guaranteed analysis and are close, but not yet lab-confirmed.

Treat this as a starting point, not a prescription

These multipliers are population averages. Two pets of identical weight can differ by 20% in what they actually need, depending on metabolism, neutering status, coat, climate and how much of the day they spend asleep. The equation gets you close; your hands finish the job.

• Feed the calculated amount for two to three weeks without changing it.
• Then check body condition: run your hands along the ribs. You should feel them easily under a thin covering, without pressing. From above there should be a visible waist behind the ribs; from the side, the belly should tuck up.
• If you can't feel ribs at all, reduce by 10% and check again in a month. If they feel sharp and prominent, increase by 10%.
• Weigh the food. A kitchen scale removes the single largest source of accidental overfeeding — the same cup of kibble can vary by a third depending on how it settles.

Treats count against this figure

Keep treats under roughly 10% of daily calories and subtract them from the meal portion. This matters far more for cats than people expect: a few pieces of cheese can be a quarter of a small cat's daily energy.

When to ask a vet instead

This calculator is for healthy animals on a maintenance diet. Don't use it to feed a pet with diagnosed kidney disease, diabetes, pancreatitis or a urinary condition, or a pregnant or nursing animal — those need veterinary direction and often a therapeutic diet. If your pet is losing weight without a change in feeding, that's a vet visit, not a calculator adjustment.