Why DIY Farmer exists
Walk into any veterinary clinic and the most common preventable health problem on the schedule is the same: overweight pets. Roughly 56% of US dogs and 60% of US cats are overweight or obese. The leading driver is almost always the same too — well-meaning owners following pet-food bag charts that overshoot real calorie needs by 20–40%.
The math to fix it isn't complicated. It's the same RER and MER formulas taught in every veterinary school. But that's not a number most owners will calculate by hand at the kitchen counter — so DIY Farmer built a calculator that does it in seconds, with the body-condition adjustments, life-stage tuning, and portion-size conversions built in.
Around that core tool, we've built 20+ vet-reviewed feeding guides, breed-specific advice, and a deep nutrition guide — because the calculator answers "how much," and pet parents also want to know "what kind" and "why."
What we stand for
Accuracy first
Every formula and recommendation is sourced from NRC 2006, WSAVA Global Nutrition Guidelines, AAFCO standards, or peer-reviewed veterinary nutrition research.
Always free
No paywalls. No premium tier. No required signups. The calculators are free and will stay free — funded by minimal, transparent affiliate links on product reviews only.
Privacy by default
The calculator runs entirely in your browser. We don't collect, store, or sell information from calculator users.
Not a vet replacement
A calculator can give you a strong starting point. Your veterinarian sees your specific pet. We're a complement to professional care — never a substitute.
Our methodology
DIY Farmer uses the following calculations and review standards:
- RER (Resting Energy Requirement): 70 × (body weight in kg)0.75
- MER (Maintenance Energy Requirement): RER × species-specific life-stage and activity multiplier from NRC 2006 tables
- Ideal weight: linear adjustment based on Purina/WSAVA Body Condition Score (~10% per BCS point above or below 5/9)
- Weight-loss calories: 1.0× RER on ideal weight (target loss 1–2% body weight/week for dogs, 0.5–1% for cats per WSAVA guidance)
- Portion sizing: daily kcal divided by user-provided kcal/cup, kcal/can, or kcal/100g
Editorial process
Every article on DIY Farmer is researched and written by Dr. Whitfield, cross-referenced against multiple veterinary sources (NRC, WSAVA, AAHA, AAFCO regulations, and peer-reviewed research), and reviewed before publication. We update content when new evidence or guidelines emerge.
If you spot something that looks wrong or outdated, let us know. We'd rather be corrected than be confidently incorrect.