How do I calculate a weight loss plan for both my cat and my dog without visiting a vet or buying a smart scale?

Paws & Pounds is 100% software-based. Use your regular home scale, complete our visual 9-point BCS assessment, and our algorithm calculates the exact RER/DER daily calories and portion size in grams. No smart scale, no vet visit required for initial assessment.

Is the Paws & Pounds app free to use?

Yes! The free tier lets you manage 1 pet, track unlimited weight entries, use the visual BCS tool, and get a daily feeding plan. Paws & Pounds Pro ($4.99/month or $29.99/year) unlocks unlimited pets, household collaboration, advanced analytics, and CSV export.

Can my partner also log feeding times?

Absolutely. Paws & Pounds Pro includes Household Collaboration — invite family members by email, and everyone in the household can log feedings, record weights, and see real-time status so nobody accidentally double-feeds your pet.

What is a Body Condition Score (BCS) and why is it better than weight alone?

Body Condition Score is a veterinary-standard 9-point scale that evaluates your pet's fat coverage through visual and hands-on checks. Unlike weight alone, BCS accounts for breed, frame size, and muscle mass. A 12-pound Maine Coon may be underweight while a 12-pound Siamese could be obese — BCS captures this difference.

How does Paws & Pounds compare to PetDesk, Pet Weight Tracker, or spreadsheet tracking?

Unlike general-purpose apps or spreadsheets, Paws & Pounds combines visual BCS assessment, veterinary-grade RER/DER calorie math, and a daily feeding plan in grams — all in one app. It covers 270+ breeds across cats and dogs, supports household collaboration, and gives you actionable portion sizes instead of just weight charts.

Which breeds does Paws & Pounds support?

Paws & Pounds includes a database of over 270 dog and cat breeds with breed-specific ideal weight ranges. If your pet is a mixed breed, you can enter a custom target weight based on your vet's recommendation.

How accurate is the calorie calculation?

Paws & Pounds uses the same RER (Resting Energy Requirement) and DER (Daily Energy Requirement) formulas used by veterinary nutritionists worldwide: RER = 70 × (body weight in kg)^0.75. We then apply species-specific, age, and neutered/intact multipliers to compute the daily calorie target.

Can I use Paws & Pounds for a puppy or kitten?

Yes. The app includes life-stage multipliers for kittens and puppies, which have higher energy requirements than adults. Select the appropriate life stage during pet setup and the feeding plan adjusts automatically.

Is my pet's data secure?

All data is stored in a secure, encrypted Supabase database with row-level security. Data is bound to your household — only invited household members can access it. We never sell or share your data with third parties.

What if my pet has a medical condition affecting their weight?

Paws & Pounds provides general nutritional guidance based on established veterinary formulas. If your pet has diabetes, thyroid issues, kidney disease, or other medical conditions, always consult your veterinarian before making dietary changes. The app's feeding plan is a starting point, not a replacement for professional veterinary advice.

What is Feline Body Mass Index (FBMI)?

Feline Body Mass Index (FBMI) is a scientifically validated formula developed to estimate a cat's body fat percentage. Unlike simple scale weight, FBMI uses rib cage and leg length measurements to account for different body frames, making it an objective way to see if a cat is carrying excess fat.

How do I measure my cat for the BMI calculator?

You will need a flexible tape measure to take two measurements: (1) Rib cage circumference around the level of the 9th rib (the widest part of the chest, just behind the front legs), and (2) Lower hind limb length, measured from the center of the kneecap (patella) down to the point of the hock/heel (calcaneus).

What is the healthy range for a cat's body fat?

A healthy, ideal range for most domestic cats is between 15% and 29% body fat. Cats with a body fat percentage below 15% are classified as underweight, while those at 30% or higher are classified as overweight or obese and face higher health risks.

How accurate is Feline BMI compared to the visual BCS scale?

FBMI is highly correlated with clinical body fat calculations. However, the visual and hands-on 9-point Body Condition Score (BCS) performed by a veterinarian is still the gold standard, as it evaluates fat deposits along the spine, ribs, and waist directly. FBMI serves as a helpful, objective home-monitoring supplement.

Why should I monitor my cat's body fat?

Obesity is a major pet health concern. Carrying excess body fat increases a cat's risk of developing feline diabetes, arthritis, hepatic lipidosis (fatty liver disease), and cardiovascular problems. Tracking body fat percentage changes over time helps you verify if a weight management program is succeeding.

Cat BMI Calculator (Feline Body Mass Index)

Science-based body fat estimator using chest and hind limb measurements. Track your cat's physical health and obesity risk without complex equipment.

By Paws & Pounds Research Team — reviewed against WSAVA/AAHA guidelines. Last updated June 25, 2026.

Your cat's measurements

Results update instantly.

Units

Rib Cage Circumference (in)

Widest part of chest, behind front legs.

Limb Length (in)

Hind leg from kneecap (patella) to heel (calcaneus).

Body Fat Estimation

Estimated FBMI (Body Fat %)

25.1%body fat

Classification

Ideal Range (15% - 29%)

What this means

Your cat falls within the optimal body fat range of 15% to 29%. This is associated with the lowest risk of weight-related health conditions.

Actionable Steps

Maintain their current activity levels and balanced diet. Re-assess their body fat percentage every 4 weeks to keep them in this healthy zone.

Estimate only — consult your vet before changing your pet's diet.

Quick answer

Feline Body Mass Index (FBMI) uses a validated mathematical formula: FBMI = ((Rib Cage Circumference in cm / 0.7062) - Limb Length in cm) / 0.9156 - Limb Length in cm. A healthy cat should have between 15% and 29% body fat. A result of 30% or more indicates excess fat and obesity. Always consult a veterinarian for nutritional and health changes.

How to measure your cat for FBMI

To calculate an accurate Feline Body Mass Index, you will need a standard flexible sewing tape measure. Try to take the measurements while your cat is standing relaxed and calm.

Rib Cage Circumference

Wrap the tape measure around your cat's chest at the level of the 9th rib. This is generally the widest part of the chest, situated just behind the front legs. Keep the tape close to the skin without pressing into the body or compressing the soft tissue.

Hind Limb Length

Measure the lower part of one of your cat's hind legs. Specifically, measure from the center of the knee cap (patella) down to the point of the hock/heel (calcaneus). Try to measure along the skeletal path while keeping the limb in a natural, bent position.

The FBMI Formula & Science

The Feline Body Mass Index is adapted from human body fat estimation techniques. It was developed and validated in peer-reviewed veterinary studies to provide a non-invasive, objective metric for body composition assessment. The exact formula is:

FBMI (%) = ((Rib Cage Circumference in cm / 0.7062) - Limb Length in cm) / 0.9156 - Limb Length in cm

Veterinary researchers found that combining the chest circumference (which expands with fat accumulation) and hind limb length (which reflects skeletal scale) offers a reliable estimate of total body fat percentage. While a 9-point Body Condition Score (BCS) assessment remains the primary clinical standard, the FBMI provides an excellent quantitative baseline for tracking progress at home.

Frequently asked questions

What is Feline Body Mass Index (FBMI)?: Feline Body Mass Index (FBMI) is a scientifically validated formula developed to estimate a cat's body fat percentage. Unlike simple scale weight, FBMI uses rib cage and leg length measurements to account for different body frames, making it an objective way to see if a cat is carrying excess fat.
How do I measure my cat for the BMI calculator?: You will need a flexible tape measure to take two measurements: (1) Rib cage circumference around the level of the 9th rib (the widest part of the chest, just behind the front legs), and (2) Lower hind limb length, measured from the center of the kneecap (patella) down to the point of the hock/heel (calcaneus).
What is the healthy range for a cat's body fat?: A healthy, ideal range for most domestic cats is between 15% and 29% body fat. Cats with a body fat percentage below 15% are classified as underweight, while those at 30% or higher are classified as overweight or obese and face higher health risks.
How accurate is Feline BMI compared to the visual BCS scale?: FBMI is highly correlated with clinical body fat calculations. However, the visual and hands-on 9-point Body Condition Score (BCS) performed by a veterinarian is still the gold standard, as it evaluates fat deposits along the spine, ribs, and waist directly. FBMI serves as a helpful, objective home-monitoring supplement.
Why should I monitor my cat's body fat?: Obesity is a major pet health concern. Carrying excess body fat increases a cat's risk of developing feline diabetes, arthritis, hepatic lipidosis (fatty liver disease), and cardiovascular problems. Tracking body fat percentage changes over time helps you verify if a weight management program is succeeding.

Track weight and body fat over time

The Paws & Pounds app helps you log measurements, track your cat's estimated body fat percentage trends, and auto-calculates precise daily calorie targets based on the latest WSAVA and AAHA standards.

Get the app Go to Calorie Calculator

Sources & further reading

Association between body condition score and body fat percentage in dogs and cats — The Journal of Nutrition, 2002
WSAVA Global Nutrition Toolkit — Calorie Calculation & Body Condition Assessment — World Small Animal Veterinary Association, 2021
2014 AAHA Weight Management Guidelines for Dogs and Cats — American Animal Hospital Association, 2014