Dog food calories, grams and cup-fill variability
My vet asked how much I feed my dog. I said 'two cups a day'. She asked which food. Same food two years, but the manufacturer changed kibble size and my dog gained 2 kg in a few months on the same 'two cups' — because the new smaller kibble packed more grams per cup. Now I weigh her food.
Dry dog food is calorie-dense. Most brands run 3.5-4.2 kcal per gram. The bag prints a feeding chart in cups, which is a volumetric measure of a solid that's shaped, sized, and packed differently in every bag. A cup of small round kibble packs 25-40% more grams than a cup of large hollow kibble.
The actual math
Adult dog daily energy requirement (rough): 30 × body weight in kg + 70, in kcal, times an activity multiplier of 1.2-1.8. A 20 kg moderately active dog needs about 30×20+70 = 670 kcal × 1.4 = 940 kcal/day. If the food is 3.8 kcal/g, that's 247 g/day.
The cup problem
A standard US measuring cup is 240 mL. Kibble varies from about 350 g/L (large hollow) to 550 g/L (small dense). So one cup = 84-132 g. That's a 60% range for the same nominal volume. Feed 'three cups' of two different foods and you might be delivering 250 g one week and 400 g the next.
The scale solution
A $15 kitchen scale eliminates the variance. Weigh the food into the bowl once, then measure how many cups that weight fills in your specific scoop — then use the scoop by cup with confidence, because you calibrated it. Redo the calibration when you buy a new bag.
Recap
Dog food feeding charts in cups are approximate. Grams-per-day is the honest unit; cups only work after you've calibrated your scoop against your current bag.
Try the converters mentioned in this article
FAQ
What about wet food?+
Same principle, but wet food is much lower calorie density (0.9-1.4 kcal/g) because most of the mass is water.
Treats?+
Should be ≤10% of daily calories. A single dental chew can be 100+ kcal — that's 10% of a small dog's daily allowance.
This article was written by The Turbo Unit Converter engineering desk (Applied metrology & engineering units) and last reviewed on 2026-07-23 against NIST SP 811 and the BIPM SI Brochure. Read our full editorial policy.