An automatic feeder dispenses food in portions, not in calories, so the setting that matters is how many portions add up to your cat's daily need. The math takes one line: calories per portion equals calories per cup divided by the number of portions in a cup. For a feeder with 1/24-cup portions and a 400 kcal/cup food, one portion is about 17 calories, and a 9 lb spayed indoor cat needs about 14 to 15 portions a day.
Below is the formula step by step, a chart by weight and food density, and a quick way to check that your feeder dispenses what the manual says.
Step 1: find the daily calories
Start from the cat, not from the feeder. A 9 lb spayed indoor adult needs about 240 calories a day; a 13 lb cat about 320. The cat food calculator gives the figure for your cat's weight, age and activity, and the cat feeding chart by weight shows the full range.
Step 2: find the portion size
The portion size is in the feeder manual. PETLIBRO, for example, states one portion as about 1/24 cup, roughly 10 grams of standard round kibble. Other brands use different volumes, so check yours rather than assuming.
Then divide: a food with 400 kcal per cup gives 400 / 24 = about 17 calories per 1/24-cup portion.
Step 3: portions per day
Divide the daily calories by the calories per portion. The chart below does it for 1/24-cup portions, adult spayed or neutered indoor cats, and three common food densities.
| Cat weight | Calories per day | 350 kcal/cup food | 400 kcal/cup food | 450 kcal/cup food |
|---|---|---|---|---|
| 7 lb | 200 kcal | 14 portions | 12 portions | 11 portions |
| 9 lb | 240 kcal | 16 to 17 portions | 14 to 15 portions | 13 portions |
| 11 lb | 280 kcal | 19 portions | 17 portions | 15 portions |
| 13 lb | 320 kcal | 22 portions | 19 portions | 17 portions |
| 15 lb | 355 kcal | 24 portions | 21 portions | 19 portions |
Split the total across the meals you schedule. Fifteen portions a day works as three meals of five, or five meals of three. Many cats do well on four or five small meals, which is close to how they eat by nature.
Check the feeder with a kitchen scale
Portions are measured by volume, so the real weight depends on the size and shape of your kibble. Large or flat kibble can come out noticeably lighter or heavier than the manual says. A two-minute check fixes that:
- Put a bowl on a kitchen scale and zero it.
- Dispense 10 portions manually.
- Divide the weight by 10 to get grams per portion.
- Your bag lists calories per kilogram: grams per portion times kcal/kg divided by 1,000 gives the real calories per portion.
Redo the check whenever you change food, since a new kibble shape changes the portion weight.
Common mistakes
- Feeder plus a full bowl. If someone in the house also tops up a bowl, the feeder schedule stops meaning anything. Pick one source of dry food.
- Forgetting wet food. If your cat also gets wet food, subtract its calories before setting the feeder. The split method is in wet vs dry cat food.
- Kitten settings on an adult. A kitten needs about twice the calories per pound of a spayed adult. Reset the schedule when the cat grows up, using how much to feed a kitten for the growth phase.
Frequently asked questions
Can an automatic feeder help a cat lose weight?
It helps with the method: the portion is fixed, and several small meals reduce begging. The target calories for weight loss should come from your veterinarian, because cutting food too fast is dangerous for cats.
Can I leave my cat alone with an automatic feeder?
For a day or two with fresh water available, many owners do. Longer absences need a person who checks in, because feeders jam, batteries run out and cats get sick.
Does the feeder work with wet food?
Standard gravity or portion feeders are for dry food only. Wet food needs a feeder designed for it, usually with a cooled or sealed tray, and should not sit out for more than a few hours.
How often should I clean it?
Wash the bowl every few days and empty and wipe the hopper when you refill it, since oils from the kibble go stale and can put cats off their food.