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Dog Weight Loss Calculator

Plan a safe weight-loss target: daily calories and how many weeks it should take.

✔ Reviewed by a licensed veterinarianContent updated 18 Oct 2026Reviewed 18 Oct 2026Sources: AAHA · WSAVA Global Nutrition Guidelines
Dog Weight Loss CalculatorFree · instant
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Quick answer. A 30 kg dog with a 25 kg ideal weight should eat about 783 kcal a day (RER at ideal weight) and lose 1–2% of body weight per week, which takes roughly 10–19 weeks. Weigh your dog every 2–4 weeks, and see your vet before starting any diet.

How to use the dog weight loss calculator

  1. Enter current weight.
  2. Enter ideal weight (use the Body Condition Score calculator if unsure).
  3. Press Calculate.

Worked example

A dog weighing 30 kg whose ideal weight is 25 kg.

Current weight
30 kg
Ideal weight (or use BCS tool)
25 kg
783 kcal/day
Calories (1.0 × RER at ideal weight)
783 kcal/day
Time at 1% per week
19 weeks
Time at 2% per week
10 weeks

Weigh your dog every 2–4 weeks and adjust with your vet. Do not go faster than 2% per week.

Example values are illustrative; this result is produced by the same calculator above.

How we calculate it

Daily kcal = 1.0 × RER(ideal weight); safe loss 1–2% body weight/week → weeks = ln(ideal/current) ÷ ln(1 − rate)

Sources: AAHA · WSAVA Global Nutrition Guidelines

Understanding your result

To lose weight safely a dog is fed the resting energy requirement of its ideal weight (70 × ideal weight in kg to the power 0.75). For a 30 kg dog with a 25 kg ideal weight this is about 783 kcal a day.

A sensible loss rate is about 1% to 2% of body weight per week. The calculator shows how many weeks it would take at each rate to reach the ideal weight.

Weigh your dog at the same time every week and adjust with your vet if the weight is not moving in the right direction.

Common mistakes

  • Cutting food drastically. Losing more than 2% a week is too fast.
  • Not counting treats, which can undo the calorie deficit.
  • Guessing the ideal weight; use the body condition score tool and ask your vet.
  • Skipping the vet check for a dog with other health problems.

Good to know

  • If weight does not change after about four weeks, ask your vet to review the plan.
  • Exercise helps, but food control does most of the work.
  • Weight loss diets work best with a diet designed for weight loss, as advised by your vet.

When to talk to your vet

  • Before starting any diet
  • If your dog loses more than 2% a week
  • If weight does not change after 4 weeks

Frequently asked questions

How fast should a dog lose weight?

About 1–2% of body weight per week is a safe pace for most dogs.

How many calories should my dog eat to lose weight?

A common vet starting point is 1.0 × RER calculated at the ideal weight, adjusted every 2–4 weeks.

How do I know my dog's ideal weight?

Use the 9-point body condition score: each point above 5 is roughly 10% extra weight.

Should I cut treats?

Keep treats within the new calorie budget — low-calorie vegetables help.

How long will my dog take to reach the ideal weight?

The calculator estimates weeks from the ideal-to-current weight ratio at 1% and 2% loss per week. Real progress varies, so weigh every 2–4 weeks and talk to your vet if weight does not change after 4 weeks.

When should I see my vet about the diet?

See your vet before starting any diet, if your dog loses more than 2% a week, or if weight does not change after 4 weeks.

Reviewed by a licensed veterinarian
Last reviewed 18 Oct 2026 · How we review

Sources

  1. AAHA (2014) Weight Management Guidelines for Dogs and Cats
  2. WSAVA Global Nutrition Guidelines (incl. 9-point BCS charts)
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Estimates only. Every pet is different — confirm with your veterinarian. If your pet may have eaten something harmful, contact your vet or an animal poison helpline now.