Pet Food Daily Portion Calculator (Dog / Cat)
Enter your pet's species (dog or cat), body weight, life stage (puppy / kitten / adult / senior / gestation / lactation) and activity level; the tool applies the NRC 2006 ("Nutrient Requirements of Dogs and Cats", National Academies Press) and WSAVA Global Nutrition Committee two-step method: (1) compute Resting Energy Requirement RER = 70 × BW(kg)^0.75 via the standard allometric scaling; (2) apply the life-stage × activity factor to get Maintenance Energy Requirement MER = factor × RER; (3) convert MER to grams of dry food using the food's energy density (kcal / 100 g, the "ME" line on the bag). RER, MER and the factor are all displayed alongside the gram total for easy cross-check with your vet's recommendation. Runs entirely client-side.
Enter a valid weight (0.1–120 kg) and food energy (50–800 kcal/100g).
Daily food portion
—
g/day
Maintenance Energy Requirement (MER)
—
kcal/day
Resting Energy Requirement (RER)
—
—
Formula
RER = 70 × BW(kg)^0.75 ; MER = factor × RER ; grams/day = MER ÷ (food kcal/100g) × 100
- · The allometric RER = 70·BW^0.75 is the modern standard across mammals (based on metabolic body mass) — established in NRC 2006 and WSAVA 2011. The older linear 30·BW + 70 is a rough approximation; this tool uses the 0.75-exponent version.
- · Dog adult-maintenance factor is 1.6 (intact). Neutered adult dogs sit closer to 1.4 — choose "adult" + "sedentary" to recover that lower number. Adult cats are 1.2 (intact); neutered cats around 1.0 — choose "adult" + "sedentary".
- · Lactation factors (dog 4.0, cat 3.0) reflect peak demand at 1–4 weeks post-whelping/queening and are *not* multiplied by activity (the demand is already maxed). Early gestation (first 5 weeks) needs are close to adult maintenance; the tool's "Gestation" stage corresponds to the last 21 days.
- · Dry-food metabolisable energy (ME) typically runs 350–450 kcal/100g; high-energy kitten formulas reach 500+; weight-loss diets are as low as 280. Bags labelled "kcal/cup" convert via "kcal/cup ÷ g/cup × 100".
- · Treat the result as a starting point — re-weigh every 1–2 weeks and adjust ±10% based on Body Condition Score (BCS, 9-point scale; ideal is 4–5/9 with palpable ribs and a visible waist).
- · Mixed wet + dry feeding: subtract the wet-food kcal from daily MER and divide the remainder by dry-food density. This tool assumes dry food only; manual subtraction needed for mixed diets.
- · References: National Research Council, "Nutrient Requirements of Dogs and Cats" (National Academies Press, 2006); WSAVA Global Nutrition Committee, "Global Nutrition Toolkit" (2011, updated 2021); Pet Nutrition Alliance, "Calorie Calculator for Dogs and Cats" (2018).
Frequently asked
My dog is overweight — can I just feed this calculated amount to lose weight?
Use the *target* weight (the BCS 4–5/9 ideal weight your vet can estimate), not the current weight, to back out the calorie target. The tool returns the MER needed to maintain that target. For active weight loss, multiply by 0.8 (a 20% reduction) and aim for 1–2% body weight loss per week. Re-weigh every 2 weeks and switch to maintenance once BCS hits 5. Don't drop calories abruptly — transition over 7–10 days and keep protein and fibre intake high.
How much do puppies and kittens eat compared with adults?
Growth-phase energy is 2–3× adult maintenance per kg body weight. NRC factors: puppy 0–4 mo = 3.0, 4–12 mo = 2.0; kitten 0–4 mo = 2.5, 4–12 mo = 2.0. Reason: rapid musculoskeletal growth plus high activity. Split into 4 meals/day under 4 months, 3 meals at 4–6 months, 2 from 6 months on. Use a growth-specific or "all life stages" food — not weight-loss or senior formulas. The tool applies the right factor automatically; before 8–10 weeks, follow your vet's or breeder's weaning plan because that transition has special protein and feeding-frequency rules.
How do I handle wet food or raw diets?
Same approach — what matters is the food's kcal/100g, not its form. Typical canned wet food is 70–110 kcal/100g (it's mostly water); frozen raw is 130–180 kcal/100g. Enter the chosen food's ME in the energy-density field and the tool converts to grams. For mixed feeding split the daily MER — e.g. 60% from dry / 40% from wet. Tip: wet food's high water content benefits kidney health (especially for cats), but the daily gram total runs 3–5× larger than dry — don't be alarmed by the volume.
The result differs from the bag's feeding chart — which one is right?
Bag charts typically run 5–20% *high* (safety margin to avoid "not enough" complaints). This tool uses NRC formulas and maintenance factors, which are closer to the individual animal's actual need. If your pet is already overweight (BCS ≥ 6/9), following the bag will keep them overweight. Use the tool's MER as your starting point and adjust ±10% every 1–2 weeks based on weight and BCS. Note: highly active dogs (working / sporting dogs running 1+ hour/day) or very lean dogs (BCS < 4) may genuinely need more than the tool indicates.
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