Dog and cat food calculator
How many grams a day and when the bag runs out — by the vets' formula, as a range rather than a single number.
How we count
Resting energy: RER = 70 × weight^0.75 kcal a day. The power formula — the linear «30 × weight + 70» is 10–17% off at the ends.
Daily need: DER = RER × K, where K depends on the species and stage.
Grams a day = DER × 1000 ÷ food energy (kcal/kg). Days = bag in grams ÷ grams a day.
An individual animal's need differs from the formula by ±30% (Merck), so we show a range. Where K is a range, we count at both ends.
K coefficients
| Stage | K |
|---|---|
| Puppy under 4 months | 3.0 |
| Puppy from 4 months | 2.0 |
| Adult, neutered | 1.6 |
| Adult, intact | 1.8 |
| Prone to weight gain | 1.2–1.4 |
| Weight loss | 1.0 |
| Pregnancy | 1.6–2.0 |
| Lactation | 2.0–6.0 |
| Working dog — light work | 2.0 |
| Working dog — moderate work | 3.0 |
| Working dog — heavy work | 6.0 |
| Stage | K |
|---|---|
| Kitten | 2.5 |
| Adult, neutered | 1.2 |
| Adult, intact | 1.4 |
| Prone to weight gain | 1.0 |
| Weight loss | 0.8–1.0 |
Example
A 20 kg neutered dog on 3700 kcal/kg food: RER ≈ 662 kcal, × 1.6 = 1059 kcal a day, 1059 × 1000 ÷ 3700 ≈ 286 g a day. A 15 kg bag lasts about 52 days.