Indoor Cat Calorie Needs

Quick answer A neutered adult cat needs about 1.2 × RER a day and an inactive cat about 1.0 × RER, where RER = 70 × kg^0.75. For a 4 kg cat that is 238 kcal against 198 kcal, 17% lower. These are starting points; adjust by body weight and condition every few weeks.

The label on a bag of cat food gives a feeding table by weight, and the table assumes an average cat. An indoor cat that spends most of the day on a sofa is not average, and the gap can add up to a few percent of body weight each season. This guide looks at the two usual factors, 1.2 for a neutered adult and 1.0 for an inactive cat, shows the calories and grams for cats from 3 to 6 kg and explains how to adjust the number using the scales rather than a formula alone. The Cat Calorie Calculator does the sum for any weight, and our guide on how much to feed a cat covers the wider picture.

The formula

Resting energy requirement (RER) is 70 × body weight in kg raised to the power 0.75. The daily energy for a cat is RER times a factor.

Cat	Factor	Meaning
Neutered adult	1.2	Typical starting point
Intact adult	1.4	Higher energy use
Inactive or obese-prone	1.0	Low activity
Kitten	2.5	Growth
Weight loss	0.8	Under vet supervision

An indoor cat is not a separate category in the factor table. It sits between 1.0 and 1.2, depending on how much it moves. A cat that runs, climbs and plays for an hour a day is closer to 1.2; a cat that sleeps most of the day is closer to 1.0.

Calories and grams for common weights

Weight	RER	At 1.2	At 1.0	Difference
3 kg	160	191 kcal	160 kcal	31 kcal (16%)
4 kg	198	238 kcal	198 kcal	40 kcal (17%)
5 kg	234	281 kcal	234 kcal	47 kcal (17%)
6 kg	268	322 kcal	268 kcal	54 kcal (17%)

In grams of a dry food at 3.8 kcal per gram:

Weight	At 1.2	At 1.0
3 kg	50 g	42 g
4 kg	63 g	52 g
5 kg	74 g	62 g
6 kg	85 g	71 g

The difference of about 10 g a day looks small, but it is 17% of the ration. Fed every day for a year, a cat that gets 63 g when it needs 52 g receives about 4 kg of extra food and over 15,000 kcal, enough in theory to put on a measurable amount of weight. These numbers come from the same formula our calculator uses; they are starting points.

Why the factor is only a starting point

Two cats of the same weight can differ by 20% or more in what they need. Age, breed, coat, the temperature of the home, muscle mass and how much the cat moves all matter. So the formula gets you to a first number and the scales do the rest.

Start at the factor that fits your cat.
Feed that amount for three to four weeks, with treats counted inside it.
Weigh the cat on a scale that reads to 10 to 50 g; see how to weigh a cat at home.
Look at the trend, then adjust by about 5 to 10% and repeat.

Adjusting by trend

What the scales show over a month	Suggested action
Steady weight and good body condition	Keep the amount
Gaining 2% or more a month	Reduce by about 5 to 10%, count treats, tell your vet
Losing weight without a plan	Do not cut; call your vet
Losing weight on a vet plan	Follow the plan’s targets and checks

For a 4 kg cat, 2% a month is 80 g. A cat that gains 80 g a month gains almost a kilogram in a year, a quarter of its weight. Our Pet Weight Change Calculator turns two weights and a time span into a percentage and a weekly pace.

Treats, toppers and table scraps

Treats are calories. The practice guideline is that treats should stay at or below 10% of the daily energy. For a 4 kg cat at 198 kcal, that is 19.8 kcal, roughly three or four small cat treats at 5 to 6 kcal each. Count dental sticks, lickable treats and bits from the plate. Our guide on how many treats a cat can have lists examples.

Wet, dry and mixed

The calories are what count, not the form. A cat eating a mix of wet and dry food must have the total under control.

Example for a 4 kg inactive cat (198 kcal)	Amount
All dry at 3.8 kcal/g	52 g
All wet at 0.9 kcal/g	220 g
Half and half by energy: 99 kcal dry	26 g dry
99 kcal wet	110 g wet

Check the kcal per kilogram on each product label, or work them out by reading the label; see how to read a cat food label. Use the Cat Food Calculator to turn calories into grams.

Making an indoor life more active

Calories out matter as much as calories in. Short play sessions, climbing structures, food puzzles and window perches raise activity. These do not change the formula; they change the outcome. If a cat becomes more active, its needs rise, and the scales will show it.

Age and life stage

The factors above are for adults. Kittens need much more per kilogram (a factor of 2.5), and they should not be on an adult plan; see kitten feeding. Older cats vary. Some lose muscle and need more protein and calories, others slow down and gain; weighing monthly and asking your vet is the safest approach, and our guide to senior cat care describes the checks.

A worked example

Mina has a 4.4 kg neutered cat that lives in a small flat and sleeps most of the day. RER = 70 × 4.4^0.75 = 70 × 3.04 = 213 kcal. At 1.2, the cat would get 256 kcal; at 1.0, 213 kcal.

Step	Working	Result
Start with the inactive factor	213 kcal	56 g of dry food at 3.8 kcal/g
Treats (10% cap)	21 kcal	Included in the 213
Weigh after 4 weeks	4.40 kg → 4.38 kg	Steady (−0.5%)
Weigh after 8 weeks	4.38 kg	Steady

The cat held its weight on 213 kcal, so Mina keeps the amount. Had she used 256 kcal from the start, the cat would have been given 20% more than it needed. The inactive factor suited this cat; the one on the label would have been too much.

Two cats, one household

Cats of different sizes need different amounts, so one scoop for both is a mistake. Take a 3 kg inactive cat and a 5 kg neutered cat.

Cat	Factor	kcal a day	Grams of 3.8 kcal/g dry food
3 kg, inactive	1.0	160	42
5 kg, neutered	1.2	281	74

Together they eat 116 g a day. If both are given 74 g, the smaller cat takes in 74 × 3.8 = 281 kcal, 76% more than its 160 kcal. That surplus is 121 kcal a day, which over a year is more than 44,000 kcal. Feed them in separate places or at separate times, or use a feeder that recognises each cat, and weigh both monthly.

What a small daily surplus does

A 4 kg cat fed 63 g of a 3.8 kcal/g food when it needs 52 g receives 11 g, or 41.8 kcal, more than it needs each day. Over a year that is about 15,257 kcal. The size of the effect on the cat depends on the cat, which is why the scales matter more than the sum.

Common mistakes

Using the bag’s chart without counting treats.
Applying 1.2 to every indoor cat.
Changing the amount without weighing.
Mixing up kcal per gram and per kilogram.
Cutting food sharply for a cat with excess weight.
Forgetting toppers and shared food.
Assuming a formula replaces the scales.

Quick summary

Neutered adult cat: 1.2 × RER; inactive: 1.0 × RER, where RER = 70 × kg^0.75.
A 4 kg cat needs 238 or 198 kcal, a difference of 17%.
In grams of 3.8 kcal/g dry food, that is 63 g or 52 g.
Count treats inside the total (up to 10%).
Weigh monthly and adjust by 5 to 10% on the trend; ask your vet before cutting.
Use the Cat Calorie Calculator.

Frequently asked questions

How many calories does an indoor cat need?

Start at 1.2 × RER for a neutered adult, or 1.0 × RER for an inactive one. A 4 kg cat is 238 or 198 kcal a day.

Do indoor cats need fewer calories?

Often, because they are less active. The inactive factor of 1.0 is 17% lower than the neutered factor of 1.2.

How do I know which factor to use?

Start with one, weigh monthly and adjust by the trend rather than relying on the factor alone.

How many grams is that?

Divide kcal by the food's kcal per gram. At 3.8 kcal/g, 198 kcal is about 52 g of dry food.

Should I cut calories if my cat is gaining?

Talk to your vet first. A small reduction, with treats counted, is usually the first step.

Do kittens or seniors follow the same factors?

No. Kittens use a higher factor (2.5) and seniors vary, so ask your vet.

Sources

Reviewed by the CalcuPaw Veterinary Review Team

Last reviewed 19 Oct 2026 · Meet the review team · This guide is general information, not veterinary advice.