kcal/cup or kcal/kg: which number on the bag do you use?
By Josh · Reviewed and updated: 2026-09-17
Pet food labels print the calorie content twice, and the two figures often look like the same number with the decimal point moved. A bag might say 3,700 kcal/kg and 370 kcal/cup — and those really are consistent with each other. But enter 3,700 where a calculator expects a per-cup figure, or 370 where it expects per-kilogram, and you get an answer ten times too large or too small. This page is about telling them apart.
The two units, and what each one is for
| On the label | Means | Use it when |
|---|---|---|
| kcal/kg | Calories in one kilogram of food, by weight | You are weighing food in grams. This is the unit most labels lead with outside the United States, and it is the more precise of the two. |
| kcal/cup | Calories in one measuring cup of food, by volume | You are scooping with a cup and not using a scale. Common on US packaging. |
| kcal per 100 g | Calories in 100 grams of food | You see it on European labels. It is simply kcal/kg divided by 10. |
They are not competing measurements. They describe the same food, in different amounts of it. The reason they cause trouble is that a calculator has to be told which one you are giving it, and the numbers are similar enough that a mistake does not look like one.
Why the error is tenfold, and why it is silent
Most adult dry food sits between 3,000 and 4,500 kcal/kg, which is 300 to 450 kcal per 100 g. Notice the pattern: the per-kilogram figure and the per-100-gram figure differ by a factor of ten, and only look like the same digits.
So 3,700 kcal/kg is 370 kcal per 100 g. Put 3,700 into a field that wanted a per-100-gram figure and the calculator believes the food contains 3,700 kcal per 100 g — ten times more energy than it does — and will tell you to feed a tenth of the correct amount. Put 370 into a field that wanted kcal/kg and it will tell you to feed ten times too much.
Converting between them
kcal/kg to kcal per 100 g: divide by 10. That is the whole conversion, and it needs no other information.
kcal/kg to kcal/cup: you also need the weight of a cup. This is where a second number comes in, because a cup is a volume and kibble density varies:
For a food of 3,700 kcal/kg at 110 g per cup: 3,700 ÷ 1000 = 3.7 kcal per gram, × 110 = 407 kcal/cup. That is why the same bag can look like 370 kcal/cup on one product and 407 on another — the calorie density is the same only if the cups weigh the same.
If the label gives kcal/cup but not grams per cup, you can measure it once: put a measuring cup on a kitchen scale, tare it, fill and level the cup, and weigh it. The cups per pound page covers that in more detail.
Which one should you actually use?
Use whichever your calculator asks for, and change the calculator's unit selector to match the label — not the other way round. Both units give the same answer once they are entered correctly:
- If you weigh food in grams — which is the more accurate way to feed, and the only sensible way for a cat — use kcal/kg or kcal per 100 g. Then the answer does not depend on how tightly a cup happens to be filled.
- If you scoop with a cup, use kcal/cup, and enter the bag's grams-per-cup value if it has one.
- If the label gives only one of the two, convert it. kcal/kg ÷ 10 gives the per-100-gram figure directly, and the per-cup figure needs only the weight of a cup.
Our calculator accepts either unit: pick kcal/cup or kcal/kg from the dropdown beside the calorie field, and it does the rest. The label-reading page covers the rest of the calorie statement — where it sits on the pack, what else is printed there, and what the guaranteed analysis does and does not tell you.
Frequently asked questions
My bag says 3,700 kcal/kg. What do I type into a calculator that wants kcal/cup?
Do not type 3,700 into a per-cup field. Either switch the calculator's unit selector to kcal/kg and type 3,700, or convert first: 3,700 kcal/kg is 370 kcal per 100 g, and the per-cup figure is (3,700 ÷ 1000) × grams per cup. At 110 g per cup that is about 407 kcal/cup.
Is kcal/kg the same as kcal per 100 g?
No — they differ by a factor of ten. kcal per 100 g is kcal/kg divided by 10, so 3,700 kcal/kg is 370 kcal per 100 g. Mixing them up is the single most common error in home portion calculation, because the two numbers look equally plausible.
Why does my bag give two different calorie numbers?
Because they are measured in different quantities of food, not because one is wrong. kcal/kg measures a weight of food; kcal/cup measures a volume. Both are correct, and they are consistent with each other once you know how much a cup of that particular food weighs.
Which is more accurate?
Feeding by weight. A cup is a volume, and the same cup can hold 90 to 130 grams of kibble depending on the food, so a cup-based figure carries that variation with it. A gram figure does not.
Where to find the calorie figure on the label →
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