Cat Calorie Needs (RER/MER)
Estimate a cat's daily energy requirement from its weight.
About Cat Calorie Needs (RER/MER)
A cat's daily energy is its resting energy requirement times a factor reflecting whether it is growing, nursing, overweight or a normal neutered adult. Indoor cats are prone to weight gain, so matching calories to a realistic target rather than an ideal number is key to keeping them at a healthy weight.
Formula
Cat Calorie Needs (RER/MER)
RER = 70 x weight^0.75; MER = RER x body-condition factor
- body condition
- life stage and weight-management multiplier
Worked example
With the default values below, Cat Calorie Needs (RER/MER) returns Resting Energy (RER) of 216. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Weightminimum 0.5 kg
- 4.5 kg
- Body conditionone of Neutered adult, Intact adult, Overweight / inactive, Kitten, Nursing
- Neutered adult
Results
- Resting Energy (RER)
- 216 kcal/day
- Maintenance Energy (MER)
- 260 kcal/day
- Body Note
- Maintenance level for a healthy adult
Step by step
- 1Values used
- 2Cat Calorie Needs (RER/MER)
- 3Resting Energy (RER)= 216 kcal/day
- 4Maintenance Energy (MER)= 260 kcal/day
- 5Body Note= Maintenance level for a healthy adult
Assumptions and limits
- The result is derived only from the 2 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 whole numbers, 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 Cat Calorie Needs (RER/MER) calculated?
RER = 70 x weight^0.75; MER = RER x body-condition factor A cat's daily energy is its resting energy requirement times a factor reflecting whether it is growing, nursing, overweight or a normal neutered adult.
Why does Cat Calorie Needs (RER/MER) matter?
Indoor cats are prone to weight gain, so matching calories to a realistic target rather than an ideal number is key to keeping them at a healthy weight.
What values do I need to enter?
This calculator takes 2 inputs: Weight, Body condition. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.