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Cat Weight Loss Calculator

Around half of cats are overweight, and excess weight raises the risk of diabetes, arthritis, and other problems. Enter your cat's current and target weight for a safe daily calorie target and a realistic timeline — but read the feline safety guidance first, because cats must lose weight slowly and under veterinary care.

Editorially Reviewed
Reviewed by the MyNubs editorial team | Last reviewed May 2026
1 Your Cat's Weight
Your cat's weight today.
Most cats' ideal weight is 8–12 lb — ask your vet to confirm.
2 Daily Calorie Target
Weight-loss feeding target
Enter your cat's current and target weight to see a safe, gradual weight-loss plan.

What this means

This is the approximate calories per day to feed for gradual loss, based on the resting needs of your cat's target weight. Cats must lose weight slowly and under veterinary supervision — see the safety note below.

See the method, safety, and FAQs →

The Calorie Target

Feed for the ideal weight, conservatively.

Go Slow

0.5–1% per week — fasting is dangerous.

Measure Meals

Stop free-feeding; weigh portions.

Vet Supervised

Always — and never let a cat stop eating.

Read this first — feline weight loss is different. Cats must lose weight slowly and under veterinary supervision. If an overweight cat eats too little or stops eating, it can develop hepatic lipidosis (fatty liver disease), a serious and potentially fatal condition that can begin within days. Never crash-diet a cat, never let one go without food, and contact your vet if your cat refuses to eat. Use this tool as a starting estimate to discuss with your veterinarian — not as a replacement for their guidance.

How the weight-loss calculation works

As with dogs, the principle is to feed for the weight you want, not the weight you have. We base the target on your cat's ideal weight:

For the timeline, we use a safe feline loss rate of just 0.5–1% of body weight per week — deliberately slow. That's why even a couple of pounds can take many months: with cats, slow is safe.

"With cats, patience isn't just a virtue — it's a medical necessity. Lose the weight too fast and you risk the very disease you're trying to prevent."

Why feline weight loss must be gradual

An overweight cat that suddenly eats far too little mobilizes body fat faster than its liver can handle. That fat builds up in the liver, causing hepatic lipidosis — fatty liver disease — which can be life-threatening and sometimes develops within days of inadequate intake. This is the single most important reason to keep weight loss slow, steady, and supervised. It's also why "just stop feeding so much" is the wrong approach for a cat.

Setting the right target weight

Most cats have an ideal weight between about 8 and 12 pounds, but the right target depends on frame and breed (a petite Siamese and a large Maine Coon differ a lot). Your vet can assess body condition score and set a realistic goal. As a rough guide, at a healthy weight you can feel the ribs with light pressure, see a slight waist from above, and see a small belly tuck — without a sagging fat pad swinging beneath the belly.

Smart approach vs common mistakes

Do thisInstead of this
Vet-supervised, gradual planDIY crash diet
Measured meals, several times a dayFree-feeding a full bowl
Higher-protein / therapeutic dietJust less of a high-carb food
0.5–1% loss per weekRapid weight loss
Calling the vet if eating stopsWaiting it out
Play and food puzzles for activityFood restriction alone

How to feed for safe weight loss

Disclaimer: This calculator provides a general starting estimate based on standard veterinary formulas (RER) and is not a substitute for veterinary care. Feline weight loss must be gradual and veterinarian-supervised because of the risk of hepatic lipidosis. Always consult your veterinarian before starting a weight-loss plan, to confirm a healthy target weight, rule out underlying conditions, and tailor the diet and pace to your cat.

Sources

Frequently asked questions

A conservative starting point is about 0.7 to 0.8 × the RER of the target weight per day. This calculator does that math and gives a daily range.

It's an estimate to discuss with your vet, who should confirm the target and supervise the plan.

Only about 0.5–1% of body weight per week — slower than dogs. A pound or two can take many months.

Rapid loss risks hepatic lipidosis, so slow and steady is essential.

If a cat eats too little, fat floods the liver faster than it can process — causing hepatic lipidosis (fatty liver disease), which can be fatal and can start within days.

Never let an overweight cat stop eating; call your vet if it refuses food.

Often a higher-protein, lower-calorie diet (frequently wet food), or a prescription weight-management food for larger losses.

Just as important: stop free-feeding, measure meals, and confirm the diet with your vet.

Once your cat reaches a healthy weight, switch to the Cat Calorie Calculator for maintenance →