Cat Food Quantity Calculator

Work out cat food quantity instantly with clear inputs, formula shown and shareable results.

About Cat Food Quantity Calculator

The same allometric rule applies to cats: RER is 70 times weight to the power 0.75, scaled by a life-stage factor and converted to grams using the food's energy density. Neutering cuts a cat's energy needs by roughly a fifth while appetite stays the same, which is why post-neutering weight gain is so common.

Formulas

Resting energy

RER kcal = 70 x (body weight kg) ^ 0.75

Daily food

grams = RER x life stage factor x 100 / kcal per 100 g

Worked example

With the default values below, Cat Food Quantity Calculator returns Food per day of 68.3. Change any input above and every figure here is recalculated in your browser.

Inputs used

Cat's weightminimum 0.3 kg: 4.5 kg
Life stageone of Adult, neutered (factor 1.2), Adult, intact (1.4), Weight loss (0.8), Kitten (2.5): Adult, neutered (factor 1.2)
Food energy densityminimum 50 kcal/100g: 380 kcal/100g

Results

Food per day: 68.3 g
Maintenance energy requirement: 260 kcal
Resting energy requirement: 216 kcal
Per meal if fed twice daily: 34.1 g

Step by step

1Values used
2Resting energy
3Daily food
4Food per day= 68.3 g
5Maintenance energy requirement= 260 kcal
6Resting energy requirement= 216 kcal
7Per meal if fed twice daily= 34.1 g

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Cat Food Quantity figure worked out?

RER kcal = 70 x (body weight kg) ^ 0.75. The same allometric rule applies to cats: RER is 70 times weight to the power 0.75, scaled by a life-stage factor and converted to grams using the food's energy density.

Why does this matter?

Neutering cuts a cat's energy needs by roughly a fifth while appetite stays the same, which is why post-neutering weight gain is so common.

What do I need to enter?

Enter cat's weight, life stage, food energy density. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.