How Much Should I Feed My Cat? The Real Math

"How much should I feed my cat?" has a real, quantitative answer — and it isn't "fill the bowl." Here's the method veterinary nutritionists actually use, translated into something you can do at home with a scale and your food bag.

Step 1: Resting Energy Requirement (RER)

A cat's baseline burn — calories needed at complete rest — follows a formula used across small-animal veterinary nutrition:

RER = 70 × (body weight in kg)^0.75

A 4 kg (8.8 lb) cat: 70 × 4^0.75 ≈ 198 kcal/day at rest. Our portion calculator does this instantly, but it's worth knowing the shape of the curve: energy scales with weight to the ¾ power, so a 6 kg cat needs nowhere near 50% more food than a 4 kg cat — roughly 30% more.

Step 2: Multiply by life stage

Notice that a neutered indoor cat — the most common case — lands near 240 kcal/day. Meanwhile a cup of average dry cat food contains 300–500 kcal. This is how house cats get fat: one overflowing "cup" can exceed a day's requirement before a single treat.

Step 3: Convert to cups — with the label, not the scoop

Find the calorie statement on your food ("3,650 kcal/kg" or "420 kcal/cup") and divide: 240 ÷ 420 ≈ 0.57 cups/day, split into 2–4 meals. Use an actual 8-oz measuring cup or — better — a kitchen gram scale; studies keep finding that scoop pourers overshoot by 20–80%.

Step 4: Adjust with the scale, not the chart

Charts and formulas produce a starting point. Your cat's metabolism runs ±20% from any formula. So:

• Weigh monthly. Steady weight is the success metric.
• Adjust by 10%. Gaining? Cut 10% for two weeks and re-weigh.
• Count treats. They must live inside the daily total — ≤10% of calories is the usual rule.
• Never crash-diet a cat. Rapid feline weight loss risks hepatic lipidosis — a serious liver disease. Weight-loss plans belong with your vet.

Wet, dry, or both?

Calorie math is identical either way. Mixed feeding is popular for practical reasons: wet food helps hydration (cats evolved as desert animals and chronically under-drink), while dry food is convenient and cheaper per calorie. Whatever you choose, the label's kcal is the bridge between our calculator and your bowl.