Before you use this tool

This calculator is an educational screening tool. It can show whether your pet's recent weight change falls within typical ranges, but only your veterinarian can confirm what is right for your pet.

Healthy, sustainable weight loss is usually gradual: about 3% to 5% of body weight per month for dogs and less than 2% of body weight per month for cats. Your veterinarian may recommend a different pace based on your pet's age, health, body condition, and diagnosis.

Contact your veterinary team right away if:
  • The weight loss was not planned or seems faster than expected.
  • Your pet is eating less, vomiting, weak, unusually tired, painful, coughing, or having trouble breathing.
  • Your cat has eaten little or nothing for 24 hours. Cats that stop eating can develop serious liver disease quickly.
How to weigh your dog or cat for a more accurate result

For the most accurate comparison, use the same scale and similar conditions for both weigh-ins.

Home weigh-ins can vary. A different scale, a recent meal, a full bladder, a heavy collar or harness, or weighing at a different time of day can make a small change look larger than it really is.

  • Use the same scale whenever possible.
  • Weigh at about the same time of day.
  • Weigh before a meal when possible.
  • Remove heavy collars, harnesses, sweaters, or carriers unless you subtract their weight.
  • For cats and small dogs, use a baby scale when available.
  • If using a home scale, weigh yourself holding your pet, then subtract your weight.
  • If the number seems surprising, weigh again before changing the feeding plan.
Green: reasonable pace Weight loss appears within a general safe range. Keep monitoring and recheck as directed.
Yellow: recheck or confirm This may appear when the change is small, the pet gained weight, the weigh-ins are close together, or the weight-loss pace is faster than expected.
Red: check entries or contact your veterinarian This may appear when the entry looks unrealistic, the dates are incorrect, the result suggests a unit mix-up, or the weight change may be too fast.
1

Choose your pet and units

2

Enter the earlier weigh-in

This is your earlier or starting weight.
3

Enter the later weigh-in

This is your more recent weight.
4

Your results

Time between
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Weight change
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Direction
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Projected per week
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Projected per month
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Additional Resources

Move from comparison to next steps

Weight comparisons help make extra pounds easier to understand. Body condition, calories, and safe weight-loss guidance help guide what to do next.

Start Here Body Condition Score Charts Check body shape and fat coverage to better understand your pet’s weight. Calories Dog & Cat Calorie Calculators Estimate daily calories and review feeding amounts. Dogs Dog Weight Loss Guide Review safer steps for dog weight loss, activity, and rechecks. Cats Cat Weight Loss Guide Learn why gradual, monitored weight loss matters for cats.
View Pet Owner Resources