hobby calculator

Cat Food Portion Calculator

Calculate your cat's daily food portion in cups and grams from body weight, life stage, and your food's calorie density.

Daily food amount comes from Resting Energy Requirement, RER = 70 × (weight in kg)^0.75, multiplied by a life-stage factor (about 1.2 for a neutered adult cat). A 10 lb neutered cat needs roughly 261 kcal per day, which is about 0.75 cups of a 350-kcal-per-cup food.

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Cat's weightlb

Life stage / activity

Calories per cup (from food label)kcal

Grams per cup (approx.)g

Feedings per day

These life-stage factors are commonly cited starting points, not a prescription — your vet may recommend a different target based on body condition score, breed, and health history. For canned/wet food, use the calories per typical can or per 100g in place of "per cup".

Results

Daily portion

0.75 cups (86 g)

Per feeding0.37 cups (43 g)

Daily calories (MER)261 kcal

Resting energy (RER)218 kcal

Bookmark this cat food calculator

Re-run this whenever your cat's weight, life stage, or food changes — a portion sized for one food doesn't carry over to a different calorie density.

Formula

Cat food portion formula

RER (kcal/day) = 70 × (weight in kg)^0.75. MER (kcal/day) = RER × life-stage factor. Portion = MER ÷ food's kcal per cup.

RER is a veterinary-standard resting energy formula, identical across species. Cats use lower life-stage factors than dogs (roughly 1.0 to 2.5) — these are commonly cited starting points, not a substitute for veterinary guidance.

Step by step

How the calculation works

1Enter your cat's body weight in pounds.
2Choose the life-stage category that best matches your cat.
3Enter the calories per cup from your specific food's label.
4Read the daily and per-feeding portion in both cups and grams.

Example

Worked example — 10 lb neutered adult cat, 350 kcal/cup food

10 lb = 4.54 kg. RER = 70 × 4.54^0.75 = 217.6 kcal. MER = 217.6 × 1.2 = 261.1 kcal. Portion = 261.1 ÷ 350 = 0.75 cups/day (85.8 g/day), or 0.37 cups per feeding across 2 feedings.

Related guides

Learn more about this calculation

Guide

How Much Should You Feed Your Dog or Cat? The RER/MER Science

The WSAVA-aligned veterinary formula behind daily feeding amounts for dogs and cats, why life stage changes the number so much, and why cats need extra caution with weight loss.

Site Guide

How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide

Learn the fastest reliable workflow for using Do The Calculation calculators, reading results, checking formulas, and using save, print, share, and export actions correctly.

Dog Feeding

Dog Food Portion Calculator

The same RER-based portioning method, tuned for dogs and their higher life-stage factors.

Age Conversion

Dog & Cat Age to Human Years Calculator

Convert your cat's age to human-equivalent years using AVMA-compliant formulas.

hobby calculator

Cat Food Portion Calculator

Calculate your cat's daily food portion in cups and grams from body weight, life stage, and your food's calorie density.

Quick actions: Save inputs, view saved runs, print, share, or export results

Saved Runs

Inputs

Cat's weightlb

Life stage / activity

Calories per cup (from food label)kcal

Grams per cup (approx.)g

Feedings per day

Results

Daily portion

0.75 cups (86 g)

Per feeding0.37 cups (43 g)

Daily calories (MER)261 kcal

Resting energy (RER)218 kcal

Bookmark this cat food calculator

Re-run this whenever your cat's weight, life stage, or food changes — a portion sized for one food doesn't carry over to a different calorie density.

Summary

Key output metrics

Daily portion

0.75 cups

86 g per day.

Per feeding

0.37 cups

43 g, split across 2 feedings.

Daily calories (MER)

261 kcal

RER 218 kcal × 1.2 life-stage factor.

Resting energy (RER)

218 kcal

70 × (4.5 kg)^0.75.

D3 visualization

Portion across life-stage factors

How the daily portion would change if this cat fell into a different life-stage category, at the same weight and food.

D3 visualization

Per-feeding split

Equal split of the daily portion across each feeding.

Feeding 143 g

Feeding 243 g

Guide

How to understand and use this calculator

Quick Answer — How Much Should I Feed My Cat?

The core formula: Resting Energy Requirement (RER, kcal/day) = 70 × (body weight in kg)^0.75. Maintenance Energy Requirement (MER) = RER × a life-stage factor. Daily portion = MER ÷ your food's calories per cup.

Quick reference (350 kcal/cup dry food):

10 lb neutered adult cat (factor 1.2) → 0.75 cups/day (85.8 g/day)
14 lb cat on a weight-loss plan (factor 1.0), 320 kcal/cup food → 0.88 cups/day (100.6 g/day)
4 lb kitten under 1 year (factor 2.5), 400 kcal/cup food → 0.68 cups/day (78.7 g/day)

Worked example: a 10 lb neutered adult cat converts to 4.54 kg. RER = 70 × 4.54^0.75 = 217.6 kcal. Applying a neutered-adult factor of 1.2: MER = 217.6 × 1.2 = 261.1 kcal/day. On a 350-kcal-per-cup food, that's 261.1 ÷ 350 = 0.75 cups per day, or about 0.37 cups per feeding split across two meals.

Cats use noticeably lower life-stage factors than dogs at the same relative body size — a cat's typical maintenance factor tops out lower than a dog's, which is one reason directly copying a dog's feeding formula onto a cat overfeeds it.

How to Use This Calculator

Enter your cat's body weight in pounds.

Choose the life-stage / activity category that best matches your cat — neutered/spayed adult is the most common default for a typical indoor companion cat.

Enter the calories per cup from your specific food's label — for wet or canned food, use the calories per typical can or per 100g in the same field, adjusting the 'grams per cup' field to match your unit.

Set the feedings per day to see the per-meal amount, not just the daily total.

Example input: Weight = 14 lb • Life stage = Weight loss • Food = 320 kcal/cup • Feedings = 2.

Output: RER = 280.0 kcal • MER = 280.0 × 1.0 = 280.0 kcal/day • Portion = 280.0 ÷ 320 = 0.88 cups/day (100.6 g/day), or 0.44 cups per feeding.

If you're also curious how your cat's age translates to human-equivalent years, the dog & cat age to human years calculator uses AVMA-compliant, size-adjusted formulas.

The Formula This Calculator Uses

Everything here is transparent, standard veterinary nutrition math — not a proprietary formula.

Step 1 — Convert weight to kilograms. Weight (kg) = Weight (lb) × 0.453592.

Step 2 — Resting Energy Requirement. RER (kcal/day) = 70 × Weight (kg)^0.75. This formula is the same across species — it's the allometric relationship between body mass and resting metabolic rate.

Step 3 — Apply a life-stage factor. MER (kcal/day) = RER × Factor. Commonly cited cat factors: 1.2 for a neutered adult, 1.4 for an intact adult, 1.0 for weight loss, roughly 1.2-1.4 for weight gain, and around 2.5 for kittens under a year old.

Step 4 — Convert to a food-specific portion. Portion (cups/day) = MER ÷ Calories per cup. The same cat needs a different measured amount on two different foods, because calorie density differs between products.

Why cat factors run lower than dog factors: cats are generally less active per unit of body weight than dogs in the categories veterinary references compare, and cat-specific studies underlying these commonly cited multipliers reflect that. Applying a dog's factor to a cat's weight will systematically overestimate the cat's calorie needs.

Step-by-Step Worked Derivation

Take the 10 lb neutered adult cat example and do it by hand.

Step 1. 10 lb × 0.453592 = 4.54 kg.

Step 2. 4.54^0.75 ≈ 3.108. RER = 70 × 3.108 = 217.57 kcal.

Step 3. MER = 217.57 × 1.2 = 261.08 kcal.

Step 4. Portion = 261.08 ÷ 350 = 0.75 cups, or 0.75 × 115 g/cup ≈ 85.8 g.

Step 5 — per feeding. Split across 2 feedings: 0.75 ÷ 2 = 0.37 cups (43 g) per meal.

Answer: about 0.75 cups (85.8 g) per day, split into two 0.37-cup feedings.

Why Indoor Cats Are Especially Easy to Overfeed

Cat obesity is common, and the math behind this calculator explains part of why: a typical indoor, neutered adult cat's factor (1.2) is one of the lowest maintenance multipliers of any common pet feeding category, yet many commercial feeding charts use a single generic recommendation that doesn't distinguish an indoor neutered cat from a more active intact one.

A relatively small weight gain is proportionally large for a cat. Because cats are small animals, an extra pound represents a much bigger percentage of total body weight than the same extra pound would for a large dog — a 10 lb cat gaining 2 lb has gained 20% of its body weight, a change that would be a much smaller percentage shift for a 65 lb dog.

Free-feeding (leaving food out all day) removes the portion control this calculator provides. If a cat has constant access to food, the calculated daily portion is only meaningful if you actually measure and offer that specific amount rather than refilling an always-full bowl.

Weight-loss plans need a lower factor, not just a smaller cup measurement of the same food. Using the weight-loss factor (1.0) is the mechanism for a deliberate, gradual reduction — cutting a cat's food sharply without veterinary guidance risks a serious condition called hepatic lipidosis in cats that stop eating enough, so any calorie reduction plan for an overweight cat should be paced and ideally vet-supervised.

Realistic Scenarios

Scenario 1 — A typical indoor companion cat. 10 lb neutered adult, 350 kcal/cup food, 2 feedings: 0.75 cups/day (85.8 g/day), 0.37 cups per feeding.

Scenario 2 — A cat on a gradual weight-loss plan. 14 lb cat, weight-loss factor of 1.0, 320 kcal/cup food, 2 feedings: 0.88 cups/day (100.6 g/day) — note this is still a real, adequate calorie amount at the reduced factor, not a severe restriction.

Scenario 3 — A growing kitten. 4 lb kitten under a year, factor 2.5, 400 kcal/cup food, 3 feedings: 0.68 cups/day (78.7 g/day) split into three roughly 0.23-cup meals — proportionally much more food per pound of body weight than either adult scenario, reflecting growth demands.

Common Feeding Mistakes

Applying a dog's feeding factor to a cat. Cat life-stage multipliers generally run lower than dog multipliers at comparable activity levels — using dog numbers overfeeds a cat.
Free-feeding without measuring at all. A calculated portion only controls calorie intake if it's actually measured and offered as a distinct amount, not left available indefinitely.
Sharply restricting an overweight cat's food without a gradual plan. Rapid calorie restriction in cats carries a real risk of hepatic lipidosis (fatty liver disease) — weight loss in cats should be gradual and ideally supervised by a veterinarian.
Reusing a cup measurement across dry and wet food. Wet food is far less calorie-dense per volume than dry kibble, so a 'cup' of one is not equivalent to a 'cup' of the other.
Ignoring treats. Treats and 'people food' contribute real calories that should count against the day's total, especially for a cat managing weight.

What This Calculator Can and Cannot Do

It can:

Estimate a starting daily calorie need using a standard veterinary RER/MER formula
Convert that calorie need into cups and grams for a specific food's calorie density
Split the daily portion across multiple feedings
Show how the portion would change under a different life-stage category

It cannot:

Diagnose obesity, underweight, or any medical condition affecting nutritional needs
Safely design a rapid weight-loss plan — cats require gradual, ideally vet-supervised calorie reduction to avoid hepatic lipidosis risk
Account for medical conditions like hyperthyroidism or kidney disease that significantly change energy needs
Know your specific food's exact calorie content without you entering it correctly from the label

The honest summary: this is a starting-point estimate built on standard formulas. Monitor your cat's actual body condition and weight trend over several weeks, and adjust the portion — or consult your veterinarian — based on real results rather than the formula alone.

Final Summary

The formula worth remembering: RER = 70 × (kg)^0.75. MER = RER × life-stage factor (roughly 1.0 to 2.5 for cats). Portion = MER ÷ food's kcal per cup.

Quick reference: a 10 lb neutered adult cat on an average-calorie dry food needs roughly 0.7-0.8 cups per day; kittens need meaningfully more per pound, and weight-loss plans should be gradual, not severe.

The one thing to actually do: measure the calculated portion rather than free-feeding, and re-check body condition every few weeks — especially for a cat on a weight-loss plan, where the pace of loss matters as much as the target.

Related tools worth a look: the dog food portion calculator for the same method applied to dogs, and the dog & cat age to human years calculator for age-stage context. For the WSAVA-aligned RER/MER science, including the hepatic lipidosis risk specific to cats, see our pet food portion guide.

Related concepts

Resting Energy Requirement (RER)

The calories an animal burns at complete rest, calculated as 70 × (body weight in kg)^0.75 — a standard starting point in veterinary nutrition for both cats and dogs.

Life-stage / activity factor

A multiplier applied to RER to estimate Maintenance Energy Requirement. Cat factors generally run lower than dog factors — from about 1.0 for weight loss to 2.5 for kittens.

Hepatic lipidosis

A serious liver condition that can develop in cats that stop eating adequately, including during overly aggressive calorie restriction — the reason feline weight-loss plans should be gradual and ideally vet-supervised.

Frequently Asked Questions

How much food should I feed my cat?+

Start with RER = 70 × (weight in kg)^0.75, then multiply by a life-stage factor — about 1.2 for a neutered adult cat. A 10 lb neutered cat needs roughly 261 kcal per day, which is about 0.75 cups of a 350-kcal-per-cup food.

What is RER in cat nutrition?+

Resting Energy Requirement — the calories a cat burns at rest, calculated as 70 × (body weight in kg) raised to the 0.75 power. It's the standard starting point before applying a life-stage multiplier to reach maintenance calories.

Why do cats need less food per pound than dogs?+

Cat life-stage factors are generally lower than dog factors at comparable activity levels — a neutered adult cat's factor is around 1.2, versus about 1.6 for a neutered adult dog. Applying a dog's feeding formula to a cat's weight tends to overfeed it.

Is it safe to put my cat on a diet?+

Weight loss in cats should be gradual and ideally supervised by a veterinarian. Rapid calorie restriction carries a real risk of hepatic lipidosis (fatty liver disease) in cats, which is why the weight-loss factor (around 1.0) still represents a real, adequate calorie amount rather than a severe cut.

How much more should I feed a kitten compared to an adult cat?+

Kittens under about a year typically use a life-stage factor around 2.5, compared to roughly 1.2 for a neutered adult — more than double, per unit of body weight, reflecting the extra energy growth requires.

Should I free-feed my cat or measure portions?+

Measuring is more reliable for weight management. A calculated portion only controls intake if it's actually measured and offered as a distinct amount — free-feeding (leaving food out all day) removes that control entirely.

Does this work for wet or canned cat food?+

Yes, if you use the calories per typical can (or per 100g) in place of 'per cup,' and adjust the weight-per-unit field to match. Wet food is far less calorie-dense per volume than dry kibble, so don't reuse a dry-food cup measurement for wet food.

Is this cat food calculator free?+

Yes — completely free, no registration, and no data leaves your browser. Every figure recalculates instantly as you change an input.

Formula

Cat food portion formula

RER (kcal/day) = 70 × (weight in kg)^0.75. MER (kcal/day) = RER × life-stage factor. Portion = MER ÷ food's kcal per cup.

Step by step

How the calculation works

1Enter your cat's body weight in pounds.
2Choose the life-stage category that best matches your cat.
3Enter the calories per cup from your specific food's label.
4Read the daily and per-feeding portion in both cups and grams.

Example

Worked example — 10 lb neutered adult cat, 350 kcal/cup food

10 lb = 4.54 kg. RER = 70 × 4.54^0.75 = 217.6 kcal. MER = 217.6 × 1.2 = 261.1 kcal. Portion = 261.1 ÷ 350 = 0.75 cups/day (85.8 g/day), or 0.37 cups per feeding across 2 feedings.

Related guides

Learn more about this calculation

Guide