Dog Food Cost per Day by Weight

Quick answer Cost per day = daily kcal ÷ kcal per gram × price per kg ÷ 1,000. A neutered 20 kg dog needs 1,059 kcal, or 294 g of 3,600 kcal/kg food, costing 1.06 a day at 3.60 per kg: about 32 a month, 387 a year. A 5 kg dog costs 0.37 a day, a 40 kg dog 1.78.

People think about dog food cost in bags, but a dog eats grams. The bag price tells you little until you know how long it lasts, and how long it lasts depends on the dog’s weight, the food’s energy and the amount fed. Converting all of it to a cost per day gives a number you can compare across foods, sizes and dogs. This guide builds that number from weight, shows how the cost changes from a 5 kg dog to a 40 kg dog at three prices and explains why a bigger dog does not cost in proportion to its weight. All prices are examples; use your own. The Dog Food Cost Calculator does the sums, and our guide to dog food cost per month covers the monthly view.

The four steps

Resting energy: RER = 70 × weight in kg^0.75.
Daily energy: for a neutered adult, 1.6 × RER.
Grams a day: daily kcal ÷ kcal per gram of the food (3,600 kcal/kg is 3.6 kcal/g).
Cost per day: grams × price per kg ÷ 1,000.

For a neutered 20 kg dog: RER = 662 kcal; daily energy 1,059 kcal; grams 294; at 3.60 per kg, 294 × 3.60 ÷ 1,000 = 1.06 a day.

The table by weight

The food is 3,600 kcal/kg for every row. The prices are examples at 2.50, 3.60 and 5.00 per kg.

Dog weight	RER (kcal)	Daily kcal (× 1.6)	Grams a day	Cost a day at 2.50	At 3.60	At 5.00
5 kg	234	374	104	0.26	0.37	0.52
10 kg	394	630	175	0.44	0.63	0.87
20 kg	662	1,059	294	0.74	1.06	1.47
30 kg	897	1,436	399	1.00	1.44	1.99
40 kg	1,113	1,781	495	1.24	1.78	2.47

Monthly and yearly totals

A month is 365 ÷ 12 = 30.4 days.

Dog weight	Monthly at 2.50	At 3.60	At 5.00	Yearly at 3.60
5 kg	7.9	11.4	15.8	137
10 kg	13.3	19.2	26.6	230
20 kg	22.4	32.2	44.7	387
30 kg	30.3	43.7	60.7	524
40 kg	37.6	54.2	75.3	650

At the middle price, the cost of feeding a dog for ten years is about 3,870 for the 20 kg dog before price rises. The range across prices is wide: the 20 kg dog on the highest price costs 537 a year, 39% more than on the middle price.

Why cost does not grow in proportion to weight

A 40 kg dog weighs eight times as much as a 5 kg dog, but costs only 4.8 times as much to feed. The reason is in the formula: energy grows with weight to the power 0.75, not 1.

Comparison	Weight ratio	Energy ratio
10 kg vs 5 kg	2.0	1.68
20 kg vs 5 kg	4.0	2.83
40 kg vs 5 kg	8.0	4.76

This does not mean large dogs are cheap to keep; other costs, such as preventive treatments and insurance premiums, can rise with size. See large dog vs small dog costs. It does mean you should not scale a food budget by weight alone.

Price per kg or price per energy

A cheaper food per kilogram can cost more per day if it is lower in energy. A food at 3,000 kcal/kg priced 3.00 per kg looks cheaper than one at 3,600 kcal/kg priced 3.60. But the 20 kg dog needs 353 g of the first (1,059 ÷ 3.0) and 294 g of the second.

Food	Price per kg	kcal per kg	Grams for 1,059 kcal	Cost a day	Cost per 1,000 kcal
A	3.00	3,000	353	1.06	1.00
B	3.60	3,600	294	1.06	1.00
C	3.00	3,300	321	0.96	0.91

Foods A and B cost the same per day. Food C is cheaper per day because its price is low for its energy. The tool that compares them is cost per 1,000 kcal; see price per 1,000 kcal and the Pet Food Price per 1,000 kcal Calculator. Cost is only one part of a choice; the food must also be complete and balanced for the dog.

Other energy factors

The 1.6 factor is for a neutered adult. Other dogs differ.

Dog	Factor	20 kg dog daily kcal	Cost a day at 3.60 per kg
Inactive adult	1.4	927	0.93
Neutered adult	1.6	1,059	1.06
Intact adult	1.8	1,192	1.19

A puppy’s factor is much higher (3.0 for young puppies, then 2.0) and the weight changes quickly, so the calculation should be repeated at each weigh-in. For weight loss, the starting energy is 1.0 × RER of the ideal weight; a 20 kg ideal weight gives 662 kcal, which costs 0.66 a day at the middle price.

Add the extras

The food in the bowl is not the whole bill. Add:

Treats and chews, priced per day from their calories.
Toppers and wet food, priced per calorie.
Delivery fees or subscription discounts.
Waste, from spoiled or refused food.

For the whole budget, see the Monthly Pet Budget Calculator and the monthly pet budget template.

A worked example

Jules has a 30 kg neutered dog and pays 52.00 for a 15 kg bag of food that lists 3,500 kcal/kg.

Step	Working	Result
Price per kg	52.00 ÷ 15	3.47
RER	70 × 30^0.75	897 kcal
Daily kcal	897 × 1.6	1,436 kcal
Grams a day	1,436 ÷ 3.5	410 g
Cost a day	410 × 3.47 ÷ 1,000	1.42
Cost a month	1.42 × 30.4	43.2
Bag lasts	15,000 ÷ 410	36.6 days
Cost per year	1.42 × 365	519

Jules finds that a bag lasts 36 days, not a month, and that the dog costs 43 a month in food. Jules adds 12 a month for treats and chews, giving 55. When the dog’s weight changes, Jules repeats the sum.

What wet food or toppers do to the bill

Adding wet food changes the cost more than most owners expect, because wet food is dear per calorie. Take the 20 kg dog (1,059 kcal) and give 20% of the energy as a wet food at 1.0 kcal/g costing 6.00 per kg, with the rest from the 3,600 kcal/kg dry food at 3.60 per kg.

Part	Energy	Grams	Cost a day
Wet (20%)	212 kcal	212 g	1.27
Dry (80%)	847 kcal	235 g	0.85
Total	1,059 kcal	447 g	2.12
Dry only	1,059 kcal	294 g	1.06

A fifth of the energy from wet food doubles the daily cost, from 1.06 to 2.12, and adds about 32 a month. That does not make it a bad choice; it makes it a choice with a price. Our guide to wet and dry dog food together explains how to combine them without overfeeding, and the Dog Wet and Dry Food Calculator works out the split.

Checking your figure against the bag

Once you have a cost per day, check it against what actually happens. A 10 kg bag at 36.00 should last 34 days for the 20 kg dog; if it empties in 28 days, the dog is eating about 357 g a day, 21% more than the 294 g calculated, and the cost per day is 1.29 rather than 1.06. The gap could be treats, a bigger scoop than you think or a food with less energy than assumed. Weigh the dog and the scoop, and check the kcal on the pack. The sum is a check on the feeding as well as a budget.

Common mistakes

Using the label’s feeding table instead of the dog’s energy need.
Comparing foods by price per kg.
Scaling cost by weight alone.
Forgetting treats, toppers and delivery.
Using 30 days for a month.
Ignoring a change in weight.
Treating the lowest price as the best choice.

Quick summary

Cost per day = daily kcal ÷ kcal per gram × price per kg ÷ 1,000.
A neutered 20 kg dog eats 294 g of a 3,600 kcal/kg food, costing 1.06 a day at 3.60 per kg.
Daily cost ranges from 0.37 (5 kg) to 1.78 (40 kg) at the same price.
Energy grows with weight^0.75, so cost is not in proportion to weight.
Compare foods by cost per 1,000 kcal.
Use the Dog Food Cost Calculator.

Frequently asked questions

How do I work out dog food cost per day?

Find the daily kcal, divide by the food's kcal per gram to get grams, then multiply by the price per gram.

Does cost grow in proportion to weight?

No. Energy grows with weight to the power 0.75, so a dog eight times heavier eats about 4.8 times as much.

What price per kg should I use?

The price you actually pay, per kg of food, divided by the bag size. Include delivery if it applies.

Does the food's energy matter?

Yes. A richer food needs fewer grams, so compare cost per 1,000 kcal instead of per kg.

Do treats change the cost?

They are part of the daily energy. Count them in the energy and price them separately.

Is this the same for puppies?

No. Puppies use a higher factor and grow, so their cost changes month by month.

Sources

NRC (2006) Nutrient Requirements of Dogs and Cats, National Academies Press: RER = 70 × kg^0.75; neutered adult factor 1.6
Pure arithmetic: cost per day = grams per day × price per kg ÷ 1,000; month = day × 365/12; year = day × 365

Reviewed by the CalcuPaw Veterinary Review Team

Last reviewed 19 Oct 2026 · Meet the review team · This guide is general information, not veterinary advice.