Jack Russells are small dogs with big engines, and feeding one well is mostly about getting the amount right. The best food for a Jack Russell is a complete recipe built around a named meat or fish ingredient, in a kibble size that suits a small mouth, with sensible calories so a busy little terrier stays lean. Get the amount right, and you can keep a Jack Russell fit for years, without spending a fortune. If you'd like a simple place to start, our small breed dog food is made for smaller mouths and appetites.
How much should a Jack Russell eat, in grams?
This is the question we get asked most about the breed, and almost always in grams rather than cups, which is the right instinct.
For an average adult Jack Russell of around 7.5kg, on roughly an hour of exercise a day, our own starting points are:
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Dry food only: about 125g a day
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Wet food only: about 410g a day
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Dry and wet together: about 85g dry plus 100g wet
Split this between one or two meals a day, and use it as a guide rather than a strict rule. You may need to feed a little more or less depending on your dog's age, activity level and body condition.
Our help centre has the full Jack Russell feeding guide, and every recipe page on our site has a feeding calculator built in, which gives you the amount for that specific food.
Swapping wet for dry: the rough conversion
Plenty of owners want to know how the two compare, and the answer sits in those numbers above. For this breed, roughly 410g of wet food does the same job as 125g of dry, which works out at around 3g of wet food replacing 1g of dry.
That ratio is handy if you mix the two, because it's easy to add a tray on top of a full bowl of kibble and accidentally feed it for a day and a half. Weigh both, and take the dry down as you add the wet. Our guide to mix feeding covers the balance. Once a tray is open, move leftovers to an airtight container in the fridge and use within two to three days, as our guide to storing wet food explains.
Why grams matter more in a small dog
Weigh food on kitchen scales rather than using a scoop. We can't recommend scoops or cups, because the bulk density of kibble differs from batch to batch, so the same scoop can hold noticeably different amounts.
The proportions are what make this matter. A 10g error on a Jack Russell's 125g day is around 8% of their food. The same 10g error on a 28kg dog eating 430g is under 3%. So the same casual scoop costs a small dog roughly three times as much, in proportion, as it costs a big one. Precision isn't fussiness in a breed this size; it's the whole job.
The treat maths nobody does
Treats should make up no more than about a tenth of your dog's daily food, and they need to come out of the meal rather than sit on top of it.
For a Jack Russell on 125g a day, a tenth is roughly 12g. That is a very small amount of food, and less than a single large dental stick in many cases. Two or three chews across a day can quietly double what your dog is eating.
A few things that help:
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Set aside a small handful of their own kibble at the start of the day and use those pieces as training rewards.
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Break bigger treats into three or four pieces. Terriers care about the event, not the size.
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If several people in the house give treats, put one person in charge of the jar or keep a tally somewhere visible.
Why the right diet pays off for this breed
There's a reason to feed this breed carefully that doesn't apply to most dogs. In a UK study of life expectancy across 30,563 dogs, Jack Russell Terriers came out as the longest-lived of the 18 breeds examined, at 12.72 years against 11.23 years for dogs overall (Teng et al., 2022).
That has a practical consequence: you may well be feeding a senior Jack Russell for five years or more, so the habits you set now run a long way.
Teeth: an honest word
Small dogs pay a price for that long life, and it shows up in their mouths. A study of 22,333 UK dogs found periodontal disease, which is gum and tooth disease, diagnosed in 12.5% of dogs in a single year, and dogs under 15kg were around 2.5 times more likely to be affected than dogs weighing 30 to 40kg (O'Neill et al., 2021). A Jack Russell at 7.5kg sits well inside that higher-risk group.
Which makes this worth saying plainly: it's a myth that dry food scrubs a dog's teeth clean as they crunch. That side of things is looked after with regular tooth-brushing and dental checks at the vet, not with anything you can change in the food bowl. What food can do is keep your dog at a healthy weight, which helps with almost everything else.
Key nutrients to look for
When you're comparing foods, a handful of things matter far more than the wording on the front of the pack.
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Named animal protein first. Meat and fish ingredients like freshly prepared chicken or salmon help maintain lean muscle on an active terrier.
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A suitable kibble size. Smaller pieces are easier for a small mouth to pick up and chew, and may encourage a dog to slow down a little.
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Omega-3 and omega-6. These are fatty acids that support healthy skin and a glossy coat.
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Sensible calorie density. Calorie density is simply how many calories are packed into each gram. Keeping it in check makes a small, lively dog much easier to keep lean.
Dry, wet or mixed: the best food types for a Jack Russell
There's no single right format. Each has its place, and the best choice comes down to your dog and your routine.
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Dry food is convenient, easy to store and simple to portion accurately by weight, which really helps with a small dog where every gram counts. Have a look at our dry dog food.
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Wet trays are higher in moisture and often more tempting for a fussier eater. Our grain-free wet trays come in trays, never tins, and are easy to portion.
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Mixed feeding gives variety and a bit more moisture, and works well as long as you weigh the total using the conversion above.
Whichever format you choose, change foods gradually rather than overnight. Swapping over about a week, shifting the balance a little at a time, gives your terrier's stomach time to adjust. If your dog has a sensitive tummy, stretching it to 10 days can help.
What to look for on the label
Whatever brand you're comparing, this quick checklist works on any pack.
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A named meat or fish ingredient at the top of the list, for example "freshly prepared chicken", rather than a broad term like "meat and animal derivatives". Both are legal descriptions;, a named ingredient simply gives you more detail about what's in the bowl.
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No artificial colours, flavours or preservatives.
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Named fat sources, plus gentle fibre or prebiotics, which are fibres that feed the helpful bacteria in the gut and support digestion.
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The words "complete" or "complementary" on the pack. A complete food gives your dog everything they need in the right balance and can be fed on its own. A complementary food, like many toppers and mixers, goes alongside a complete food rather than replacing it. For everyday feeding, you want complete.
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A recipe matched to your dog's life stage, and to any sensitivities where relevant.
Is Harringtons a good choice for a Jack Russell?
For many Jack Russells, yes. As an active breed, they tend to do well on a complete, balanced diet with quality ingredients and portions matched to their lifestyle.
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Our small breed recipes come in a kibble size made for little mouths, which is the practical starting point for a dog this size. There's more on the wider question in our guide to choosing food for small breeds.
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Our grain-free recipes are built around freshly prepared meat and fish ingredients as the number one ingredient, and made without wheat, dairy or soya.
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For dogs with sensitivities, our Just 6 recipes keep things simple with six key ingredients, which can make it easier to see how your dog gets on. If soft stools are the main issue, our food for sensitive stomachs gathers the recipes made with gentler digestion in mind.
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Our Superfoods recipes add functional extras like spinach, sweet potato and seaweed, good ingredients doing a bit more in the bowl.
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Our grain-free wet trays are made using our FreshCook® process and work nicely for mixed feeding.
Everything is made here in the UK, developed by our in-house pet nutritionists, free from artificial colours and flavours, and honestly priced. No compromise, which is rather the point. Our recipes are also available on subscription, so the right bag turns up before you run out.
Common food sensitivities in Jack Russells
Jack Russells are a generally hardy breed, but any dog can react to something in its food.
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Signs to watch for include itchy skin, recurring ear trouble, and loose stools.
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The language matters here. True food allergies are actually quite rare, so it's more accurate to talk about food sensitivities.
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If your dog keeps getting itchy, have a chat with your vet. Where a food sensitivity is suspected, a simple, limited-ingredient recipe like Just 6 can be useful during a vet-guided elimination diet, where you strip the diet back and reintroduce foods one at a time. Our guide to why your dog might be itching has more.
Feeding a Jack Russell through life
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Puppy: small tummies do better with little and often, so smaller meals spread across the day suit a growing pup. Feed to the weight you expect them to reach rather than their current weight. Our puppy food is made for growing dogs, our guide to how much to feed a puppy covers portions, and our guide to moving onto adult food covers the switch.
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Adult: keep portions weighed and match the amount to how active your terrier really is. Neutering matters too, as many dogs need a little less afterwards, so keep an eye on body condition and adjust. There's more in our guide to neutering and spaying.
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Senior: given how long this breed tends to live, you may be feeding a senior for several years. A gentler, lighter recipe often suits them as they slow down. Take a look at our senior dog food.
Keeping your Jack Russell at a healthy weight
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Weigh meals in grams. As the maths above shows, small errors matter more in a small dog.
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Keep treats inside the daily allowance, and break bigger ones into pieces.
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Do a regular hands-on body condition check. You should be able to feel the ribs easily under a light covering, and see a clear waist when you look down from above.
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Keep exercise regular and matched to a properly active terrier. Our dog walking guide has ideas for keeping a busy dog busy.
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If your Jack Russell needs to lose a noticeable amount of weight, do it alongside your vet rather than cutting food sharply on your own.
Ingredients and foods to avoid
Some everyday foods should stay out of any dog's bowl, and size makes this more pressing in a terrier.
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Toxic foods including grapes, raisins, onions, garlic, chocolate, macadamia nuts and xylitol, a sweetener found in some sugar-free products. Because a Jack Russell is small, it takes less of any of these to cause harm than it would in a big dog. Our guide to foods that are poisonous for dogs has the full list.
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Artificial colours, flavours and preservatives.
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Seasoned, fatty or salty human leftovers, which can upset the stomach or worse.
You may also have seen worry about a possible link between grain-free food and a heart condition called dilated cardiomyopathy, or DCM, where the heart muscle weakens. It's a fair question, so here's the honest position. As of 2024, the US Food and Drug Administration has not found a proven causal link, and describes the picture as complex. Where there has been a signal, it has pointed towards diets very high in pulses and legumes such as peas and lentils, rather than the absence of grain itself. If you'd like to look into it properly, we cover the topic in do dogs need grain-free food?
References
O'Neill, D. G., Mitchell, C. E., Humphrey, J., Church, D. B., Brodbelt, D. C., & Pegram, C. (2021). Epidemiology of periodontal disease in dogs in the UK primary-care veterinary setting. Journal of Small Animal Practice, 62(12), 1051-1061. https://onlinelibrary.wiley.com/doi/full/10.1111/jsap.13405
Teng, K. T., Brodbelt, D. C., Pegram, C., Church, D. B., & O'Neill, D. G. (2022). Life tables of annual life expectancy and mortality for companion dogs in the United Kingdom. Scientific Reports, 12, Article 6415. https://doi.org/10.1038/s41598-022-10341-6
U.S. Food and Drug Administration. (2024). Questions & answers: FDA's work on potential causes of non-hereditary DCM in dogs. https://www.fda.gov/animal-veterinary/animal-health-literacy/questions-answers-fdas-work-potential-causes-non-hereditary-dcm-dogs
