Dog Feeding Calculator by Weight
For a 40 lb (18.14 kg) spayed or neutered adult dog eating a dry food at 380 kcal per 100 g, the daily portion is 862–985 kcal — that is 227–259 g a day, or 2.27–2.59 cups if one cup of that food weighs 100 g.
Enter your dog's details
Use the weight your dog is today. Supported range: 4–200 lb (1.8–90.7 kg).
The four bands and their factors are the published reference set; the factor table below lists them with their source.
Read it off the pack. Many labels print kcal per kilogram — divide by 10. 3,800 kcal/kg is 380 kcal per 100 g. Supported range: 250–600.
This is the number that decides your scoop, and almost no label prints it. If your pack shows both kcal per cup and kcal per kilogram, you can compute it exactly — see the section below. Supported range: 40–250 g.
Meals split the daily portion; they do not change the daily total.
Everything is calculated in your browser. The numbers you type are not uploaded and not stored.
Daily portion at that weight
Daily calories at that weight
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Enter a weight to see the daily portion in grams and cups.
A cup is a volume, not a weight. One US customary cup is 236.6 mL by definition — but how many grams of kibble that volume holds depends entirely on the food. Two dry foods can both be “one cup” and differ by 20 g or more, which is enough to over- or under-feed by a quarter. Weighing in grams removes that variable completely; this page prints both so you can see the gap.
Put your dog's weight in below and the grams and the cups recompute as you type.
Constants this page uses, and where each one comes from
| Constant | What it is | Named source |
|---|---|---|
| 70 | RER scaling constant, 70 × kg0.75 | AAHA 2021, Box 1, as reproduced on the Association for Pet Obesity Prevention calculator page (read 2026-10-19) |
| 0.75 | exponent applied to body weight in kilograms | AAHA 2021, Box 1, as reproduced on the Association for Pet Obesity Prevention calculator page (read 2026-10-19) |
| 1.4–1.6 | factor band for typical adult, spayed or neutered | AAHA 2021, Box 1, as reproduced on the Association for Pet Obesity Prevention calculator page (read 2026-10-19) |
| 1.6–1.8 | factor band for typical adult, intact | AAHA 2021, Box 1, as reproduced on the Association for Pet Obesity Prevention calculator page (read 2026-10-19) |
| 1.0–1.2 | factor band for sedentary / prone to weight gain | AAHA 2021, Box 1, as reproduced on the Association for Pet Obesity Prevention calculator page (read 2026-10-19) |
| 1.6–2.0 | factor band for light work | AAHA 2021, Box 1, as reproduced on the Association for Pet Obesity Prevention calculator page (read 2026-10-19) |
Where to start
Start with the Dog Calorie Calculator: it needs only a weight and a condition, so it returns a daily calorie range before you have read a single food label. That range is the input every other Calories & Feeding tool expects, including this page.
How the figures are worked out
Four steps connect your dog's weight to the amount you scoop: resting energy requirement, a life-stage factor, the food's energy density, and the weight of one cup. Every number on this page comes from those four, and each is printed so you can redo the arithmetic by hand.
Step 1 — resting energy requirement (RER)
RER = 70 × (body weight in kg)0.75
RER is what a dog burns at complete rest — the energy cost of staying alive, before activity is added. kg is body weight in kilograms (1 lb = 0.45359237 kg). A 40 lb dog is 18.14 kg, so RER = 70 × 18.140.75 ≈ 615 kcal/day.
Step 2 — the life-stage factor
daily kcal = RER × factor
The factor accounts for everything RER leaves out. The four bands below are the published reference set for healthy adult dogs; they are ranges, not single numbers, because two dogs of the same weight genuinely differ.
| Band | Factor | Notes |
|---|---|---|
| Typical adult, spayed or neutered | 1.4–1.6 × RER | The default band for most pet dogs. Neutering lowers the requirement relative to an intact dog of the same weight. |
| Typical adult, intact | 1.6–1.8 × RER | Intact dogs sit one band higher. |
| Sedentary / prone to weight gain | 1.0–1.2 × RER | The low band. Use it when the dog is already carrying extra body fat and the goal is to hold the current weight, not to lose it. |
| Light work | 1.6–2.0 × RER | Sporting and working dogs. Heavy work sits above this table and needs a plan built with your veterinary team. |
The RER equation and these four maintenance bands are published in the AAHA 2021 Nutrition and Weight Management Guidelines (Box 1), as reproduced on the Association for Pet Obesity Prevention's adult dog feeding calculator page (read 2026-10-19). The bands are starting reference points, not minimum or maximum safe intakes, and they are not added together.
Step 3 — turning kcal into grams
grams per day = (daily kcal ÷ kcal per 100 g) × 100
A pack that prints “3,800 kcal/kg” is the same as 380 kcal per 100 g. Divide the daily kcal by that figure and multiply by 100 to get the grams to weigh out.
Step 4 — turning grams into cups
cups per day = grams per day ÷ grams per cup
This is the step almost every feeding calculator leaves to you, and it is the one where the errors live. The next section is entirely about it.
The part no feeding calculator gives you: how many grams are in one cup of your food
Feeding calculators accept a calorie figure from the pack and hand back a portion. Some ask for kcal per cup and return cups; some ask for kcal per 100 g and return grams. Almost none of them reconcile the two, which means the person with a kitchen scale and the person with a measuring cup are calculating from different numbers and neither can check the other.
When a label prints both kcal per cup and kcal per kilogram, the weight of one cup falls out of the label's own two figures — no guess, no lookup table:
grams per cup = (kcal per cup ÷ kcal per 100 g) × 100
Work it through with example label figures. Each line below is arithmetic on two numbers a pack could print — not a statement about any real product.
| Example label prints | kcal per cup | kcal per 100 g | Grams per cup |
|---|---|---|---|
| Example A | 404 | 388 | 104.1 g |
| Example B | 360 | 396 | 90.9 g |
| Example C | 436 | 393 | 110.9 g |
| Example D | 380 | 380 | 100.0 g |
Four labels, and one cup runs from 90.9 g to 110.9 g — a spread of 20 g, or 22% of the lightest cup. That is the whole problem in one table: the word “cup” on a scoop is not a unit of anything until you attach a gram figure to it.
What a wrong cup weight costs you
Hold everything else still — a 40 lb (18.14 kg) spayed adult at 862–985 kcal/day on a food at 380 kcal per 100 g, so 227–259 g a day — and change only the assumed weight of a cup:
| If one cup is… | Cups per day | Per meal (2 meals) | Off by |
|---|---|---|---|
| 80 g | 2.83–3.24 | 1.42–1.62 | +25.0% |
| 90 g | 2.52–2.88 | 1.26–1.44 | +11.1% |
| 100 g | 2.27–2.59 | 1.13–1.30 | reference |
| 110 g | 2.06–2.36 | 1.03–1.18 | −9.1% |
| 120 g | 1.89–2.16 | 0.94–1.08 | −16.7% |
| 130 g | 1.74–1.99 | 0.87–1.00 | −23.1% |
Every row is 227–259 g/day divided by the gram figure in the first column. The percentage is that row against the 100 g row; because cups scale as 1 ÷ grams-per-cup, the low end and the high end of the range move by the same percentage.
Takeaway: getting the cup weight wrong by ±30% moves the scoop by −23% to +25%. Nothing else on this page has that much leverage — not the activity band, not the rounding of the calorie figure. If you only fix one input, fix this one, or better, weigh the food.
If the label does not print both figures
Some packs print kcal per cup only. In that case the label has given you a volume and an energy figure but no weight, and there is no arithmetic that recovers the gram figure — you have to weigh a cup yourself once, on a kitchen scale, and write it down. Some print kcal per kilogram only; the same one-time weighing settles it. And if a pack prints grams per cup directly, that figure is the one to use, and it matches the derivation above by construction.
Two published equations, and which one this page uses
There is not one equation for a dog's daily energy — there are two in wide use, and they are built differently. One is a resting requirement multiplied by a life-stage factor; the other is a single direct equation for a typical adult.
| Form | Equation | What it gives an 18.14 kg (40 lb) dog |
|---|---|---|
| Resting requirement × factor | 70 × kg0.75 × 1.4–1.6 | 862–985 kcal/day |
| Direct adult equation | 110 × kg0.75 | 967 kcal/day |
The 110 × kg0.75 form is the maintenance-energy equation published in the Waltham Centre pocket book of essential nutrition for cats and dogs (2009), and is reproduced in the footnote of the Dog Food Advisor's dog food calculator page (read 2026-10-19). The 70 × kg0.75 resting form and the factor bands are the AAHA 2021 reference set, as reproduced on the APOP calculator page (read 2026-10-19).
Put side by side, the two land 44 kcal/day apart at 40 lb (967 against 923, the midpoint of the factor band) — about 12 g of food at 380 kcal per 100 g. That is a rounding error next to the cup-weight table above, which is the honest way to rank the two problems: if you are measuring by the cup, the cup is where your accuracy goes, not the equation. This page uses the resting-requirement-plus-factor form because it is the one that also produces a band rather than a single number, and because it extends to the sedentary and working bands.
Worked example: 40 lb (18.14 kg), spayed adult, 380 kcal per 100 g, 100 g per cup, 2 meals
The same arithmetic the calculator above runs, written out so you can check it with a pencil.
| Step | Calculation | Result |
|---|---|---|
| 1. Convert weight | 40 × 0.45359237 | 18.14 kg |
| 2. Resting energy requirement | 70 × 18.140.75 | ≈ 615 kcal/day |
| 3. Factor band (spayed or neutered adult) | from the published factor table | 1.4–1.6 × RER |
| 4. Daily calories | 615 × 1.4 … 615 × 1.6 | 862–985 kcal/day |
| 5. Grams per day at 380 kcal per 100 g | 862 ÷ 380 × 100 … 985 ÷ 380 × 100 | 227–259 g/day |
| 6. Grams per cup from the label's own figures | (kcal per cup ÷ kcal per 100 g) × 100 | example: 100.0 g |
| 7. Cups per day | 227 ÷ 100 … 259 ÷ 100 | 2.27–2.59 cups |
| 8. Per meal, 2 meals | 226.72 ÷ 2 … 259.11 ÷ 2 | 113–130 g, or 1.13–1.30 cups |
Step 6 is where a real pack's figures go; 100.0 g here is the arithmetic result of a label that prints 380 kcal per cup and 380 kcal per 100 g, used as the worked example.
Weight → grams → cups, at your food's settings
Two tables, both recomputed from the weight, life-stage band, energy density and cup weight you set above. The first sweeps body weight; the second sweeps energy density. Neither exists on the feeding calculators that rank for this term — they answer one dog at a time.
Updates live as you change the weight, life stage, density or cup weight above.
| Weight | kg | RER | Daily kcal | Grams/day | Cups/day | Per meal |
|---|
RER = 70 × kg0.75, rounded to the nearest whole kcal. Grams and cups use the density and cup weight from the form.
The same dog across five energy densities
Denser food means fewer grams and fewer cups for the same calorie target. This is the table to check before you assume a new bag is “about the same” as the last one.
| Density | Typical product | Grams per day | Cups per day | Per meal |
|---|
Calories are unchanged across the rows — only the mass and the volume move. Density labels follow the same example convention as the derivation table above.
Frequently asked questions
How many grams are in one cup of dog food?
There is no fixed answer, and that is the point: a cup is a volume (236.6 mL by definition), not a weight. The three example labels earlier in this page worked out to 90.9 g, 100.0 g, 104.1 g and 110.9 g per cup — a 22% spread. If your pack prints both kcal per cup and kcal per kilogram, divide the first by the second and multiply by 100 and you have the exact figure for your food.
Should I feed by grams or by cups?
Grams, whenever you can. A gram is the same on every scale; a cup depends on the food, on how full the scoop is, and on whether the kibble has settled in the bag. The gram figures in the tables above are the target; the cup figures are there so you can translate if a scale is not an option.
My label only prints kcal per kilogram. How do I get kcal per 100 g?
Divide by 10. 3,800 kcal/kg is 380 kcal per 100 g. The calculator accepts kcal per 100 g directly, so that is the number to type in.
My label only prints kcal per cup, and I want to weigh the food. What do I do?
Weigh one level cup once, on a kitchen scale, and record the grams. That single number converts every cup figure on the pack into a gram figure forever, and it is the same number the derivation above would give you if the pack also printed kcal per kilogram.
Does this feeding calculator work for puppies, pregnant dogs or seniors?
No. The four factor bands on this page are for healthy adult dogs. Growing puppies, pregnant or nursing bitches, and dogs on a weight-loss plan run on different factors, and a senior dog's requirement often drops. Those life stages need a plan built with your veterinary team.
How many meals should the daily amount be split into?
The daily total does not change with the number of meals — only the size of each one. Two meals is the common default for adult dogs; three or four is often easier for large breeds or dogs that gulp. The per-meal row in each table is the daily amount divided by the meal count you chose.
How accurate is the calorie estimate itself?
It is a starting band, not a measurement. The factor ranges exist precisely because two dogs of the same weight and life stage can need different amounts. Weigh your dog every few weeks and adjust the portion up or down to hold the body condition you and your veterinary team agree on.
Is this the same as a dog food calculator or a portion calculator?
Yes — those are the same job described from different angles. This page takes the weight, applies the published maintenance bands, and returns the daily portion in grams and cups; other sites use the words “dog food calculator”, “portion calculator” or “feeding calculator” for tools that return calories, or grams, or cups, but rarely all three with the cup weight shown.
What this page deliberately doesn't do
- It doesn't choose a food. Energy density and cup weight are inputs you read off your own pack. No brand is recommended anywhere on this page.
- It doesn't cover puppies, pregnancy, nursing or weight loss. Those are different factor sets. This page is adult maintenance only, and it says so in the factor table.
- It doesn't model individual variation beyond the published bands. Two dogs of the same weight can sit at opposite ends of the band; only body condition over weeks tells you which.
- It doesn't replace a veterinary feeding plan. Illness, prescribed diets, and body-condition work all need a veterinary team, not a calculator.
- It doesn't guess your cup weight. If the pack does not print enough to derive it, the page tells you to weigh one cup rather than inventing a number.