CalculatorDex
Health

Dog and Cat Calorie Calculator

Work out how many calories your dog or cat needs each day from their weight and life stage, and how many grams of their food that is.

Rules last checked 10 November 2026Every step shown2 sources

Your numbers are saved in this browser.

For weight loss, use the target weight your vet suggests.

kcal per 100 g

Printed on the pack. Leave at 0 to skip the food amount.

Calories a day

1,059 kcal

Resting energy need
662 kcal
Food a day
294 g
Per meal
147 g

A 20 kg dog (adult, neutered) needs about 1,059 kcal a day, which is 294 g of this food, or 147 g a meal over 2 meals.

How it's worked out

  1. Resting energy (RER)70 × 20^0.75662 kcal
  2. Adult, neutered662 × 1.61,059 kcal
  3. Food1,059 kcal ÷ 360 kcal × 100 g294 g a day
  • This is a starting point, since every pet is different. Weigh yours every few weeks and adjust the amount.
  • Treats count too; keep them under a tenth of the day's calories. Ask your vet before putting a pet on a diet.

How it is worked out

First the resting energy requirement (RER), the energy needed at rest: 70 × body weight in kg raised to the power 0.75. That is multiplied by a factor for the pet's life stage, from 0.8 for a cat losing weight to 3.0 for a young puppy. Vets' guidelines give a range for some adult factors (1.4 to 1.6 for a neutered dog, for example); the calculator uses the commonly quoted figure, so a less active pet may need a little less.

Treats and extras

Treats, chews and table scraps all count. Keep them small, and cut the main meals a little on days with more of them.

Questions people ask

How many calories does a 16 kg dog need?

A neutered adult dog of 16 kg needs about 896 kcal a day. Its resting need is 70 × 16^0.75 = 560 kcal, times 1.6.

How do I turn calories into grams of food?

Find the kcal per 100 g on the pack and divide the daily calories by it, then multiply by 100. At 400 kcal per 100 g, 896 kcal is 224 g a day.

Why do neutered pets need fewer calories?

Neutering lowers energy needs, so neutered pets put on weight more easily on the same amount of food.

Is this exact?

No. It's a starting point. Weigh your pet every few weeks, adjust the amount to keep them at a healthy weight, and ask your vet before starting a diet.

Formula and rules last checked 10 November 2026Written and tested by the CalculatorDex teamReport a problem

Sources: Pet Nutrition Alliance: Calculating calories based on pet needs (PDF) · AAHA 2021 Nutrition and Weight Management Guidelines: energy requirement calculations (PDF)