Dog Weight Loss Calculator
Vets don't slim dogs by feeding 'a bit less'. They set calories to 1.0 × RER of the target weight and aim for 1–2% loss per week. This calculator does exactly that — portion, rate and timeline.
Enter your dog's details
Enter current weight, then the target your vet set (or ~the weight where ribs are easily felt).
Weight-loss portions by target weight
| Dog weight | RER (resting) | Daily target | Food per day | Per meal (×2) |
|---|---|---|---|---|
| 3 kg · 7 lb | 160 kcal | 160 kcal | 47 g | 23 g |
| 5 kg · 11 lb | 234 kcal | 234 kcal | 69 g | 34 g |
| 8 kg · 18 lb | 333 kcal | 333 kcal | 98 g | 49 g |
| 10 kg · 22 lb | 394 kcal | 394 kcal | 116 g | 58 g |
| 15 kg · 33 lb | 534 kcal | 534 kcal | 157 g | 78 g |
| 20 kg · 44 lb | 662 kcal | 662 kcal | 195 g | 97 g |
| 25 kg · 55 lb | 783 kcal | 783 kcal | 230 g | 115 g |
| 30 kg · 66 lb | 897 kcal | 897 kcal | 264 g | 132 g |
| 35 kg · 77 lb | 1,007 kcal | 1,007 kcal | 296 g | 148 g |
| 40 kg · 88 lb | 1,113 kcal | 1,113 kcal | 327 g | 164 g |
| 50 kg · 110 lb | 1,316 kcal | 1,316 kcal | 387 g | 194 g |
| 60 kg · 132 lb | 1,509 kcal | 1,509 kcal | 444 g | 222 g |
Calories = 1.0 × RER of TARGET weight, on a 340 kcal/100 g weight-control food. No treat removal in this table — keep treats inside the calorie number, under 10%.
The 1–2% rule, and why crash diets backfire
Healthy fat loss in dogs runs at 1–2% of body weight per week. Faster restriction risks exactly what you don't want: muscle loss alongside fat, nutrient deficiencies (the calories shrink faster than the vitamin content), and a miserable, food-obsessed dog whose owner gives up by week three.
The mechanics are simple: calories are set for the dog you're trying to reveal, not the dog you have. Feed RER of target weight, weigh every 2 weeks on the same scale, and if two consecutive weigh-ins show no loss, trim the portion 10%. Plateau adjustments are normal — as the dog gets lighter, the target number shrinks too.
See a vet first, not last, if your dog is obese (not just chubby), over 7 years old, or on medication — hypothyroidism and Cushing's both masquerade as 'just fat'.
Check body condition first
Before you set a target weight, score your dog on the 9-point body condition scale: ideal is 4–5 — ribs easily felt under a thin fat cover, a waist visible from above, a tuck from the side. If you can't feel the ribs, the target weight is lower than you think; if ribs show, the dog may not need to lose at all. Re-score every two weeks as the weight comes off — the scale tells you the kilos, the ribs tell you the truth.
When to stop
Stop and talk to your vet if weight falls faster than 2% a week at two checks running, if your dog goes off their food, or if they are diabetic, pregnant, nursing or on medication — those cases need a vet-set target, not a generic deficit. Reaching the target is a stop point too: switch to the maintenance factor (1.6 × RER) at the new weight instead of continuing to cut.
How to use this calculator
Enter current weight
Enter your dog's current weight.
Enter the target weight
Enter the target weight your vet set — calories are calculated at 1.0 × RER of the TARGET weight, never the current one.
Enter food energy density
Enter the food's energy density (kcal per 100 g) from its label.
Read the portion and timeline
Read the daily portion, the expected loss rate of 1–2% of body weight per week, and the estimated time to target.
Frequently asked
How much should I feed my dog to lose weight?
Calories equal to 1.0 × RER of target weight — for a 24 kg target, 692 kcal/day. Weigh the food; 'a bit less of the usual' almost never creates a real deficit.
How fast should a dog lose weight?
1–2% of body weight per week. A 28 kg dog should lose roughly 280–560 g weekly; consistently faster is a reason to add food back, not celebrate.
Why is my dog not losing weight on the plan?
Usually: treats and extras outside the number, a food denser than assumed, or thyroid disease. Audit extras honestly first — one dental chew can be 90 kcal.
How much should a 20 kg dog eat to lose weight?
Safe loss is calculated at the TARGET weight: RER 662 kcal and about 195 g/day of a weight-control food (340 kcal/100 g). A healthy rate is 1–2% of body weight per week.
Why has my dog's weight loss stalled?
Almost always invisible calories: treats, scraps and 'just a bit more'. Weigh the portion, log everything, and if it stalls for 3 weeks, cut 10%.
Related calculators
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RER & MER explained and calculated — resting vs daily energy, per life stage.
Dog Food Calculator by Weight
Portions for every weight, 1 kg to 90 kg — table first, calculator second.
Dog Nutrition Calculator
Protein and fat grams per day, checked against AAFCO minimums.