It is tempting to assume that a big dog costs proportionally more than a small one, so that a dog eight times heavier is eight times the expense. It is not that simple. Food follows a law of its own, and other costs follow different rules: some stay the same whatever the size, some jump at a weight band and some are charged by breed. This guide shows what size does to each line of the dog budget, works through a comparison between a 5 kg and a 40 kg dog with example prices and explains how to get a real figure for the dog you have in mind. The prices are placeholders; the food arithmetic is the formula the site uses. The Cost of Owning a Dog Calculator takes your own monthly figures.
Food: the one cost with a formula
Resting energy is 70 × weight^0.75. A neutered adult needs 1.6 times that.
| Dog | RER (kcal) | Daily kcal (× 1.6) | Grams a day (3.6 kcal/g) | Food a year at 3.60 per kg |
|---|---|---|---|---|
| 5 kg | 234 | 374 | 104 | 137 |
| 10 kg | 394 | 630 | 175 | 230 |
| 20 kg | 662 | 1,059 | 294 | 387 |
| 30 kg | 897 | 1,436 | 399 | 524 |
| 40 kg | 1,113 | 1,781 | 495 | 650 |
The 40 kg dog weighs eight times the 5 kg dog and eats 4.76 times as much. Per kilogram of body weight, the small dog eats more: 374 ÷ 5 = 75 kcal per kg against 1,781 ÷ 40 = 45 kcal per kg. See dog food cost per day by weight for the full table.
Items priced by size
Some items are cheaper when small and dearer when large, with no formula but a price list. Example placeholders:
| Item | Small dog (5 kg) | Large dog (40 kg) | Ratio |
|---|---|---|---|
| Crate | 60 | 120 | 2.0 |
| Bed | 25 | 70 | 2.8 |
| Harness | 20 | 40 | 2.0 |
| Lead and collar | 15 | 25 | 1.7 |
| Bowls | 8 | 15 | 1.9 |
The ratios cluster around two, well below the weight ratio. The crate guide what size crate does my dog need shows how to size one, and the dog crate size chart gives the sizes. These items are bought once and replaced occasionally, so their effect over a dog’s life is modest compared with food and vet care.
Items priced by weight band
Parasite treatments and some other medicines are sold in weight bands. A small dog’s band can cost much less than a large dog’s, and the difference can be a multiple. The numbers differ by product and country, so ask your vet and pharmacy for the price of each band for the dog you have in mind.
| Item | Small dog (5 kg) | Large dog (40 kg) | Ratio |
|---|---|---|---|
| Monthly preventive (example) | 10 | 25 | 2.5 |
| Per year | 120 | 300 | 2.5 |
Some practices also price anaesthesia and dental work by weight. The routine care total in routine vet costs can therefore differ with size; ask the practice how it prices.
Items priced by breed or coat
Grooming and boarding can be priced by size, coat or breed. A short-coated small dog may need little grooming while a large long-coated dog needs professional help; the reverse also occurs. See how much dog grooming costs and pet boarding costs. Insurance premiums are often set by breed, age and location, and larger breeds can carry higher premiums, but it depends on the insurer.
Putting it together: year one
A simple example for year one of a small and a large dog. Prices are placeholders. The routine vet care and insurance lines are left out, because they depend heavily on your own quotes.
| Line | Small dog | Large dog |
|---|---|---|
| Food | 137 | 650 |
| Crate | 60 | 120 |
| Bed | 25 | 70 |
| Harness | 20 | 40 |
| Preventives (12 months) | 120 | 300 |
| Total | 362 | 1,180 |
The large dog costs 3.3 times as much on these lines. Food accounts for 38% of the small dog’s total and 55% of the large dog’s. The ratio is larger than the food ratio of 4.8 only because the other lines are also dearer, and smaller because the one-off items are a fixed part. Add your own vet and insurance quotes to complete the picture; our guide to the monthly cost of a dog lists the remaining lines.
Lifetime view
Size also changes how long the budget runs. Larger dogs have, on average, shorter lives, which reduces the number of years of cost; see how long dogs live and why big dogs age faster. A lifetime figure should multiply the yearly cost by the expected years, with price rises. Individual dogs vary a great deal, so use a range.
| Dog | Yearly running cost (food + preventives, example) | Years | Total |
|---|---|---|---|
| Small | 257 | 14 | 3,598 |
| Large | 950 | 10 | 9,500 |
(Years are illustrative planning figures, not predictions for any dog.) Even with fewer years, the large dog costs more overall in this example. The food and preventive lines are only part of the total, and the real cost for any dog includes the unexpected.
How to price the dog you are considering
- Estimate the adult weight from the breed or parents, or ask the shelter’s vet.
- Calculate daily kcal and food cost with the Dog Food Cost Calculator.
- Ask your vet for the price of preventives for that weight band.
- Ask for quotes for the crate, bed and harness at the adult size.
- Ask insurers for a quote by breed and age.
- Add it up in the Monthly Pet Budget Calculator.
A puppy’s adult weight is an estimate, so run the sums for the lower and upper end of the range.
A worked example
Nora is choosing between a small terrier-type dog (6 kg adult) and a large cross (32 kg adult). She gets a quote for each line.
| Line | 6 kg dog | 32 kg dog |
|---|---|---|
| Food (kcal ÷ 3.6 × 3.60 per kg × 365) | RER 70 × 6^0.75 = 268; × 1.6 = 429 kcal; 119 g; 156 a year | RER 70 × 32^0.75 = 942; × 1.6 = 1,507 kcal; 419 g; 551 a year |
| Preventives | 130 | 290 |
| Crate, bed, harness | 105 | 220 |
| Insurance (quote) | 360 | 540 |
| Year-one total | 751 | 1,601 |
Nora’s large dog costs 850 more in year one, 2.1 times the small dog. She decides that the difference fits her budget, but she also asks her landlord about size limits before going further, because cost was not the only constraint. The numbers took ten minutes and shaped the conversation.
Cost per kilogram of dog
Dividing the yearly food bill by body weight shows how the cost per kilogram falls as the dog gets bigger.
| Dog | Food a year | Per kg of body weight |
|---|---|---|
| 5 kg | 137 | 27.4 |
| 10 kg | 230 | 23.0 |
| 20 kg | 387 | 19.4 |
| 40 kg | 650 | 16.3 |
A small dog costs more to feed per kilogram, and a large dog costs more in total. Both facts are true, which is why a budget based on a single number misleads.
Questions to ask each provider
- How does the vet price parasite control and medicines: by weight band or flat?
- Does the boarding kennel or sitter charge by size?
- Does the groomer price by breed, coat or size?
- Does the insurer rate by breed and age, and what is the premium for the adult weight?
- Does the training class or daycare price by size?
Write the answers beside the example prices and replace them. That list is worth more than any average, because the answers are for your dog and your area.
Common mistakes
- Scaling every cost by weight.
- Ignoring the 0.75 power in food.
- Forgetting items priced by weight band.
- Using a puppy’s weight instead of its adult weight.
- Leaving out insurance quotes.
- Treating example prices as real.
- Ignoring lifespan differences.
Quick summary
- Food energy scales with weight^0.75: a 40 kg dog eats 4.8 times a 5 kg dog, not 8 times.
- At 3.60 per kg that is 650 against 137 a year.
- Items priced by size cost about twice as much; weight-band items can cost more.
- Example year-one total: 362 for a small dog and 1,180 for a large dog, before vet and insurance quotes.
- Get real quotes for the adult weight.
- Use the Cost of Owning a Dog Calculator.
Frequently asked questions
Do large dogs cost more than small dogs?
Usually, in food and in items priced by size or weight. The gap is smaller than the weight ratio for food, because energy scales with weight to the 0.75 power.
Why does a dog eight times heavier not eat eight times as much?
Resting energy is 70 × kg^0.75. Eight to the power 0.75 is 4.76.
Which costs depend on size?
Food, crate, bed, harness, some parasite treatments and sometimes boarding, grooming and insurance. Ask each provider how they price.
Are vet bills higher for large dogs?
Some are, such as anaesthesia and medicines priced by weight. Ask your vet how costs are set.
Do small dogs live longer?
On average, yes, which changes the total over a lifetime. See the lifespan guide; individual dogs vary.
Are these prices accurate?
They are examples for the arithmetic. Replace each with a quote.
Sources
- NRC (2006) Nutrient Requirements of Dogs and Cats, National Academies Press: RER = 70 × kg^0.75
- Provider quotes (parasite control, boarding, grooming and insurance are priced by weight band or breed by many providers)
Related calculators
- Cost of Owning a Dog CalculatorAdd up the one-off and monthly costs of a dog to see the first-year, yearly and lifetime cost.
- Dog Food Cost CalculatorSee what it costs per day, month and year to feed your dog, from its calorie need and the price of the bag.
- Monthly Pet Budget CalculatorAdd up your monthly pet costs to see the monthly and yearly total.
Keep reading
- Dog Food Cost per Day by WeightDog food cost per day from weight: daily kcal ÷ kcal per gram × price per kg, with a table for 5 to 40 kg dogs at three prices, plus monthly and yearly totals.
- Monthly Cost of a Dog: What People ForgetThe monthly cost of a dog beyond food: parasite control, vet care, insurance, grooming, daycare and replacements, with a template for annual bills.
- How Much Does It Cost to Own a Dog?Work out the real cost of owning a dog with your own numbers: one-off costs, monthly costs, first-year and lifetime totals, hidden extras and ways to plan.
- Pet Sitter vs Boarding: Cost ComparisonHow to compare boarding, drop-in visits and an overnight sitter: rate × nights, a 3 to 14 night table, extras, break-even rates and what price cannot tell you.