Most adult indoor cats need between 180 and 350 calories a day depending on weight and whether they are spayed or neutered. For a 9 lb spayed cat on typical 400 kcal/cup dry food, that is about 0.6 cups a day, which is noticeably less than the amount printed on many bags.
Below is the chart by weight, the formula it comes from, and the three things that change the number more than brand choice ever does.
The chart
Daily calories for adult cats, with dry-food cups shown at 400 kcal per cup. Check your own label, since dry foods range from 350 to 450.
| Weight | Spayed / neutered | Intact adult | Cups (spayed, 400 kcal) |
|---|---|---|---|
| 7 lb | 200 kcal | 235 kcal | 0.50 |
| 9 lb | 240 kcal | 280 kcal | 0.60 |
| 11 lb | 275 kcal | 320 kcal | 0.69 |
| 13 lb | 310 kcal | 360 kcal | 0.78 |
| 15 lb | 345 kcal | 400 kcal | 0.86 |
The cat food calculator runs the same math for any weight, life stage and label, including wet food and metric labels.
The formula behind the chart
Veterinary nutrition starts from resting energy requirement:
RER = 70 x (body weight in kg)0.75
Daily need is then RER multiplied by a factor for life stage:
- Growing kitten: 2.5
- Spayed or neutered adult: 1.2
- Intact adult: 1.4
- Very active or outdoor: 1.6
- Senior, 10 to 11 years and up: 1.1
The exponent matters and is the reason a cat twice as heavy does not need twice the food. Metabolic rate scales to roughly the three-quarter power of body mass, a relationship that holds across mammals from mice to elephants.
Why the bag says more
Feeding guides on packaging are written for a broad population that includes intact, active and outdoor cats. Most cats reading this are none of those. A spayed indoor cat has the lowest energy needs of any adult category, and following a generic chart is one of the most common routes to a slowly overweight cat.
Manufacturers also have no incentive to underestimate. This is not a conspiracy, just a structural bias worth knowing about.
The three things that change the number
Spay or neuter status. The single largest factor after weight. Metabolic needs drop 15 to 20% after the procedure, and portions very often do not. If your cat gained weight in the year after being neutered, this is almost always why.
Indoor versus outdoor. A cat with outdoor access can need a third more than the same cat kept inside. Indoor cats sleep 16 hours a day and walk a few hundred metres.
Age. Kittens need more than double the adult factor per pound. Seniors need slightly less, though very old cats sometimes need more again as absorption declines, which is worth discussing with a vet rather than guessing.
Check the cat, not the chart
Any chart is a starting estimate. The measurement that matters is body condition, and it takes ten seconds:
- Ribs: you should feel them easily with flat fingers, without pressing. Visible ribs mean underweight; ribs you cannot find mean overweight.
- Waist: from above, there should be a visible narrowing behind the ribcage.
- Profile: from the side, the belly should tuck up slightly rather than hang level.
Adjust the portion by about 10% and reassess after a month. Weight in cats should change slowly, and rapid restriction is genuinely dangerous, since cats losing weight too fast can develop hepatic lipidosis.
Frequently asked questions
Should I free feed or use set meals?
Set meals give you control over the daily total, which is the entire point of measuring. Free feeding a spayed indoor cat is the most reliable way to produce an overweight one. Two to three measured meals suits most cats.
My two cats eat different amounts. Is that normal?
Yes. Individual metabolism varies by around 20% between cats of the same weight and status. Feed each to their own body condition, and separate them at mealtimes if one eats the other's food.
How do I measure accurately?
A kitchen scale beats a measuring cup, because scoops vary and kibble settles differently each time. Weighing the daily portion once and marking the level on a container is a reasonable compromise.
What about treats?
Treats count, and they add up faster than most owners expect. Keep them under 10% of daily calories and subtract them from the meal portion rather than adding them on top.
Does the same math work for dogs?
The RER formula is the same; the multipliers differ. See how many cups of dog food per day for the dog version.