Dog and Cat Weight Loss Calculator (Safe Rate and Calories)
Enter your pet’s current and ideal weight to plan a safe weight-loss programme.
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Dog and Cat Weight Loss Calculator (Safe Rate and Calories) by TheCalcTools
How the Dog and Cat Weight Loss Calculator (Safe Rate and Calories) works
The AAHA guidelines suggest feeding the resting energy requirement of the ideal weight (1.0 × RER for dogs, 0.8 × RER for cats) and losing 1% to 2% of body weight a week, then adjusting every 2 to 4 weeks.
Losing a percentage each week means the amount shrinks as the pet gets lighter, so the time to target is ln(ideal ÷ current) ÷ ln(1 − rate). Cats should not lose weight fast: rapid loss can cause fatty liver disease.
The formula
Worked example
Using the default values shown in the calculator:
| Species | Dog |
|---|---|
| Current weight (kg) | 30 |
| Ideal weight (kg) | 25 |
| Target loss per week (% of body weight) | 1.5 % |
- A 30 kg dog with an ideal weight of 25 kg: feed 783 kcal a day.
- At 1.5% a week it takes about 13 weeks; the first week’s loss is 0.45 kg.
Result:
| Daily calories during weight loss | 783 |
|---|---|
| Weeks to reach the ideal weight | 13 |
| First week's loss (kg) | 0.45 |
| Total to lose (kg) | 5.0 |
| Excess weight | 20% |
Frequently asked questions
How fast should my dog lose weight?
1% to 2% of body weight a week. For a 30 kg dog that is 0.3 to 0.6 kg a week.
Should I just feed less of the same food?
Cutting a regular food a lot can short-change protein and nutrients. Vets often recommend a weight-loss diet; ask yours before starting.
Sources and further reading
- AAHA 2021 guidelines: Weight reduction in the obese pet
- AAHA 2021 Nutrition and Weight Management Guidelines for Dogs and Cats
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.