How fresh dog food subscriptions calculate your dog's portions

5 min read

Fresh food subscriptions like The Farmer's Dog, Nom Nom, and Ollie sell personalization as their edge. You fill out a quiz, and an "algorithm" hands back a daily calorie number and a pre-portioned pack. It sounds proprietary. It mostly is not. The inputs these quizzes ask for, weight, age, activity level, spay or neuter status, and body condition, are the same variables vets have used for decades to estimate calorie needs. Here is the formula behind that math, and how to check whether your own number holds up.

The formula behind almost every calorie recommendation

Veterinary nutrition starts with Resting Energy Requirement, or RER: the calories a dog burns at complete rest. The standard formula is:

RER = 70 × (body weight in kg)^0.75

RER alone underestimates what a living, moving dog actually needs, so it gets multiplied by a life stage and activity factor to produce Maintenance Energy Requirement, or MER:

MER = RER × activity factor

The activity factor is where individual differences come in. Typical ranges used across veterinary references:

• Intact adult, average activity: about 1.8
• Neutered or spayed adult, average activity: about 1.6
• Weight loss goal: about 1.0
• Prone to weight gain or mostly sedentary: 1.2 to 1.4
• Active or working dogs: 2.0 to 5.0, depending on workload
• Puppies under 4 months: about 3.0
• Puppies over 4 months: about 2.0

These ranges are starting points, not fixed constants. A vet may adjust a specific dog's factor up or down based on body condition and how the dog responds over the following weeks.

What the subscription quiz is actually collecting

When a fresh food company asks for your dog's weight, life stage, activity level, spay or neuter status, and body condition, it is gathering exactly what it needs to plug into the formula above. The "algorithm" is real in the sense that it is doing the arithmetic and rounding to a deliverable pack size, but the underlying model is the same RER and MER framework used in veterinary practice, not a novel discovery unique to any one brand.

Where the numbers can legitimately differ

If you run your own dog's numbers and land on a different daily calorie count than what your subscription assigned, that is not automatically a mistake on either side. A few reasons the numbers move:

• Pack size rounding. Food arrives in fixed pack sizes, so a company may round your dog's exact number up or down slightly to fit a deliverable pack.
• Built-in margin. If your dog's goal is weight loss or gain, the assigned number is deliberately offset from plain maintenance, not an error.
• Different activity assumptions. A generic calculator defaults to an average multiplier. A subscription's quiz answers about your specific dog can shift that multiplier up or down.
• Different formula variants. Some fresh food and raw feeding guides use a simpler body-weight percentage method (commonly 2 to 3 percent of body weight per day) instead of the RER and MER formula. Both are legitimate, and they will not always agree exactly.

A worked example

Take a 45 lb (20.4 kg) spayed adult dog with average activity:

• RER = 70 × 20.4^0.75 = 70 × 9.6 = about 672 kcal/day
• MER = 672 × 1.6 (neutered adult factor) = about 1,075 kcal/day

That 1,075 kcal/day figure is the target most calculators, and most subscription algorithms, would land on for a dog with this profile before any weight-management adjustment.

How to check your own subscription's number

Find your dog's assigned daily calories in your subscription account (usually under your plan or portion details), then compare it against your own calculation for your dog's weight, life stage, and activity level. A gap of 10 to 15 percent in either direction is normal and often reflects a deliberate weight-management margin. If the gap is much larger, or your dog is trending the wrong direction on weight despite following the assigned portion, that is worth a call to your vet rather than a DIY adjustment. Individual metabolism can vary by a similar margin even between two dogs of identical weight and life stage, so neither number is automatically "more correct."

You can run this same calculation for your own dog, and test how the number shifts under different activity or body condition assumptions, using the free dog food calculator.

Frequently asked questions

Do fresh food subscriptions use a secret formula to calculate portions?

No. They collect the same inputs vets have used for decades and run them through some version of the standard RER and MER formulas above. The personalization is real. The underlying math is public veterinary science, not proprietary technology.

Why does my subscription's calorie number not exactly match a generic calculator?

Small differences are normal. Companies may round to fit pack sizes, build in a margin for weight goals, or use a slightly different activity multiplier than a generic calculator defaults to. A gap of 10 to 15 percent is not a sign of an error on either side.

When should a mismatch worry me?

If the numbers differ by more than about 25 percent, or your dog is gaining or losing weight unexpectedly while eating the recommended amount, check in with your vet rather than adjusting the math yourself.

Can I use this same math to check a raw or homemade diet?

Yes. RER and MER are diet-agnostic. They tell you how many calories your dog needs regardless of whether the source is kibble, canned food, fresh food, or a raw diet. What changes between diets is how many calories are packed into each cup, can, or pack, which comes from the food's label or manufacturer, not from this formula.