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How Much Should I Feed My Dog? Daily Food Calculator by Weight

Find out exactly how many grams of dry dog food to feed your adult or senior dog per day. Uses the veterinary RER/MER formula (NRC). Enter weight and life stage — get instant results.

🗓️ Updated June 2026 Reviewed by Martín Rodríguez

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Reviewed by: Martín Rodríguez (editorial policy ) · Last reviewed: Jun 20, 2026

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This calculator estimates your dog's daily dry food requirement (in grams) based on body weight and life stage. It uses the Resting Energy Requirement (RER) method recommended by veterinary nutritionists: RER (kcal/day) = 70 × (weight_kg)^0.75, then multiplied by a life-stage factor (MER), then divided by the food's kilocalorie density (3.5 kcal/g for standard dry kibble). The result is a gram-per-day amount. Use it when you adopt a new dog, your pet's weight changes, or you switch food brands.

When to use this calculator

Calculating the correct daily ration after adopting a rescue dog whose ideal weight is just being established.
Adjusting portion sizes after neutering an adult dog (factor drops from 1.8 to 1.6, saving ~10–15% food daily).
Figuring out how much to feed a senior dog (7+ years) whose metabolism has slowed.
Scaling portions for a large breed (30–50 kg) to avoid accidental overfeeding.

MER Life Stage Factors for Daily Dog Food Calculation

Life Stage	MER Factor	Description
Active adult / intact	1.8	Uneutered dog with daily activity
Neutered adult / normal	1.6	Neutered or moderately active dog
Senior healthy (7–10 yrs)	1.4	Slowed metabolism, less active
Older senior / overweight	1.2	10+ years old or prone to weight gain

Fuente: Merck Veterinary Manual / NRC Nutrient Requirements of Dogs and Cats (2006)

How it works

How to Calculate Daily Dog Food Portions

The correct daily food amount is calculated in three steps, following NRC (National Research Council) guidelines endorsed by WSAVA and AAHA:

1. Resting Energy Requirement (RER)

RER (kcal/day) = 70 × weight_kg^0.75

This allometric formula (used in the Merck Veterinary Manual) estimates the minimum calories a dog needs at complete rest to maintain vital functions. The 0.75 exponent comes from Kleiber's Law: metabolic rate scales to body mass to the power of 0.75, not linearly — so a 40 kg dog doesn't need twice the calories of a 20 kg dog (it needs ~1.68×).

2. Maintenance Energy Requirement (MER)

MER = RER × Life Stage Factor

Life Stage	MER Factor	Description
Active adult / intact	1.8	Uneutered dog with daily activity
Neutered adult / normal	1.6	Neutered or moderately active dog
Senior healthy (7–10 yrs)	1.4	Slowed metabolism, less active
Older senior / overweight	1.2	10+ years old or prone to weight gain

Source: Merck Veterinary Manual / NRC Nutrient Requirements of Dogs and Cats

3. Convert Calories to Grams of Food

Most quality dry dog foods contain 3,000–4,000 kcal/kg. This calculator uses 3,500 kcal/kg as a standard default:

Daily Food (g) = MER ÷ 3.5 kcal/g

If you know your brand's exact calorie density (printed on the bag), calculate: Daily grams = MER ÷ (your_kcal_per_kg ÷ 1,000).

Quick Reference Table (neutered adult, standard dry food)

Dog Weight	RER (kcal/day)	MER × 1.6 (kcal/day)	Daily Grams
5 kg	234	374	107 g
10 kg	394	630	180 g
15 kg	536	858	245 g
20 kg	668	1,069	305 g
25 kg	794	1,271	363 g
30 kg	916	1,465	419 g
40 kg	1,149	1,839	525 g
50 kg	1,373	2,197	628 g

How to Interpret the Result

The central result assumes ideal body condition: you can feel the ribs with light pressure but cannot see them.

The ±15% range covers individual metabolic variation.

Split into 2 meals per day for adult dogs; 2–3 smaller meals for seniors.

Always weigh portions with a kitchen scale — cup measurements can be off by 20–30% depending on kibble shape.

Common Mistakes to Avoid

1. Using actual weight for obese dogs: feed based on your vet's target weight, not current weight.
2. Ignoring actual calorie density: premium kibble at 4.2 kcal/g will overfeed by ~20% if you assume 3.5 kcal/g.
3. Forgetting treats: treats should not exceed 10% of daily caloric intake.
4. Not adjusting after spay/neuter: gonadectomy reduces resting metabolism by ~25–30%, so reduce the factor from 1.8 to 1.6 immediately post-surgery.

Example: 30 kg Neutered Labrador

Weight: 30 kg → RER = 70 × 30^0.75 = 70 × 12.83 = 898 kcal/day

Life stage: Neutered adult → MER factor = 1.6

MER = 898 × 1.6 = 1,437 kcal/day

Standard dry kibble: 3,500 kcal/kg → 3.5 kcal/g

Daily food = 1,437 ÷ 3.5 = 411 g/day (range: 349–473 g/day at ±15%)

411 g/day for a 30 kg neutered adult Labrador (range: 349–473 g/day)

Disclaimer: Los resultados son orientativos y no reemplazan la consulta veterinaria. Antes de tomar decisiones con impacto, consultá con un veterinario matriculado.

Frequently asked questions

How much dry dog food should I feed a 10 kg dog per day?

A 10 kg neutered adult dog needs approximately 180 g/day of standard dry kibble (3,500 kcal/kg). Active intact adult: ~203 g/day (factor 1.8). Senior 7–10 years: ~157 g/day (factor 1.4). The math: RER = 70 × 10^0.75 = 394 kcal; MER = 394 × 1.6 = 630 kcal; Food = 630 ÷ 3.5 = 180 g.

How many grams per day should a 20 kg dog eat?

A 20 kg neutered adult dog needs approximately 305 g/day of standard dry food. Active intact: ~346 g/day. Senior: ~268 g/day. Calculated as: RER = 70 × 20^0.75 = 668 kcal, MER = 668 × 1.6 = 1,069 kcal, Food = 1,069 ÷ 3.5 = 305 g.

How much less should a senior dog eat compared to an adult?

A healthy senior (7–10 years) uses a MER factor of 1.4 vs 1.6 for a neutered adult — roughly 12–15% fewer calories. For an older senior (10+ years) or overweight dog, the factor drops to 1.2, meaning up to 25–33% fewer calories than a same-weight active adult.

Why does the formula use the 0.75 exponent on body weight?

The 0.75 exponent represents metabolic body weight, based on Kleiber's Law (1932): basal metabolic rate across mammals scales to body mass to the power of 0.75, not linearly. A 40 kg dog needs only ~1.68× the calories of a 20 kg dog, not 2×. This prevents overfeeding larger breeds.

Does neutering change how much my dog should eat?

Yes. Neutering reduces resting metabolic rate by roughly 25–30%, so the MER factor drops from 1.8 (intact active adult) to 1.6 (neutered adult). If you don't adjust the portion after surgery, the dog will gain weight within months. A 15 kg dog goes from needing ~274 g/day to ~243 g/day.

How do I find the calorie density of my dog's food?

Check the 'Calorie Content' panel on the bag — it lists kcal/kg or kcal/cup. Quality dry foods typically range from 3,000 to 4,000 kcal/kg. This calculator uses 3,500 kcal/kg as the standard. To adjust: Daily grams = MER ÷ (your brand's kcal/kg ÷ 1,000).

How many meals per day should I give my dog?

Adult dogs (1–7 years): 2 equal meals per day (morning and evening) is the standard recommendation and reduces bloat risk in deep-chested breeds. Senior dogs: 2–3 smaller meals to ease digestion. Puppies under 6 months: 3–4 meals per day for stable blood sugar. Avoid free-feeding (leaving food out all day) as it makes portion control impossible.

Does this calculator work for wet (canned) food?

Yes, but substitute the correct energy density. Wet food typically contains 0.8–1.2 kcal/g due to its high moisture content (75–82% water), versus 3.5 kcal/g for dry kibble. Divide MER by your canned food's actual kcal/g to get correct grams. A 30 kg active dog needing 1,437 kcal/day would need approximately 1,200–1,800 g of wet food daily.

At what age is a dog considered 'senior'?

It depends on size: small breeds (under 10 kg) are senior at 10–12 years; medium breeds (10–25 kg) at 7–8 years; large breeds (25–45 kg) at 6–7 years; giant breeds (over 45 kg) at 5–6 years. Larger dogs age faster and their diet should be adjusted sooner.

How do I know if I'm feeding the right amount?

Ideal body condition: you can feel the ribs with light pressure but cannot see them. If ribs are visible, the dog is underweight; if you cannot feel them even with firm pressure, it is overweight. Adjust the ration by ±10% and reassess in 2 weeks. Always weigh portions with a kitchen scale — never estimate by eye or cup.

Sources & references

Methodology & trust

Editorial

Calculadora de mascotas revisada por el equipo editorial de Hacé Cuentas, contrastada con National Research Council — Nutrient Requirements of Dogs and Cats (2006), según nuestra política editorial y metodología.

Updates

Última revisión: June 20, 2026. Los parámetros se verifican periódicamente con las fuentes citadas.

Privacy

Calculations run 100% in your browser. We do not store or transmit your data.

Limitations

Indicative results. For critical decisions, consult a professional.

📌 How to cite this calculator

Rodríguez, M. (2026). How Much Should I Feed My Dog? Daily Food Calculator by Weight. Hacé Cuentas. https://hacecuentas.com/dog-food-calculator-by-weight

Contenido bajo licencia CC-BY 4.0 — reutilizable citando la fuente con enlace a Hacé Cuentas.

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