How much should an adult Brittany Spaniel weigh?

A healthy adult typically weighs between 13.5kg and 18kg, with males generally toward the higher end and females toward the lower end. This is a general range rather than a fixed target, and body condition matters more than the exact number.

At what age is a Brittany Spaniel fully grown?

Most Brittanys reach close to their adult weight by around ten to twelve months old, though some continue to fill out slightly in muscle and body shape for a few months beyond that.

How can I tell if my Brittany is a healthy weight?

Feel for their ribs with light pressure — you should be able to feel them without pressing hard — and look for a visible waist from above. Both together are a more reliable guide than comparing their weight to a chart alone.

Should I worry if my Brittany doesn't match the weight chart?

Not necessarily, as long as their body condition looks healthy and their weight has not changed suddenly. A gradual difference from a general chart is common between individual dogs; a sudden, unexplained change is the thing worth mentioning to your vet.

Brittany Spaniel weight chart

A healthy adult Brittany Spaniel typically weighs between 13.5kg and 18kg. Here's how that weight is usually reached, and how to read a chart against your own dog, stage by stage from puppy through to a fully grown adult, rather than expecting one number to fit every dog.

Typical weight by age

A Brittany Spaniel puppy grows steadily through its first year, generally reaching somewhere close to its adult weight by around ten to twelve months, with a healthy adult male or female typically settling between 13.5kg and 18kg. Males tend to sit toward the higher end of that range and females toward the lower end, though individual dogs vary.

Any weight chart is a guide built from averages across the breed, not a target for your specific dog. A Brittany that is a little lighter or heavier than the chart suggests, but has a good body condition and energy level, is not automatically a cause for concern.

Reading body condition alongside the number on the scale

A number on a chart tells you less than actually feeling your dog. You should be able to feel their ribs with light pressure, without them being visible, and see a clear waist when looking down at them from above. A Brittany that meets those two markers is generally at a healthy weight regardless of exactly where they sit on a chart.

Weigh your dog every few weeks during their growing months, and every couple of months as an adult, rather than relying on a single measurement — a trend over time tells you far more than one number does.

When a weight difference is worth mentioning to your vet

A sudden, unexplained change in weight in either direction, rather than a gradual difference from a chart, is the thing worth flagging to your vet — sudden weight loss or gain can be an early sign of several conditions worth ruling out.

Your vet weighs your dog at every routine visit and can tell you, based on your individual dog's history rather than a general chart, whether their weight is tracking normally.

Common questions

How much should an adult Brittany Spaniel weigh?: A healthy adult typically weighs between 13.5kg and 18kg, with males generally toward the higher end and females toward the lower end. This is a general range rather than a fixed target, and body condition matters more than the exact number.
At what age is a Brittany Spaniel fully grown?: Most Brittanys reach close to their adult weight by around ten to twelve months old, though some continue to fill out slightly in muscle and body shape for a few months beyond that.
How can I tell if my Brittany is a healthy weight?: Feel for their ribs with light pressure — you should be able to feel them without pressing hard — and look for a visible waist from above. Both together are a more reliable guide than comparing their weight to a chart alone.
Should I worry if my Brittany doesn't match the weight chart?: Not necessarily, as long as their body condition looks healthy and their weight has not changed suddenly. A gradual difference from a general chart is common between individual dogs; a sudden, unexplained change is the thing worth mentioning to your vet.

Sources

Written against guidance published by UK veterinary and welfare organisations. Always confirm specifics with your own vet.

Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.