How big do Saint Bernards get?

How big is a fully grown Saint Bernard?

A fully grown Saint Bernard is one of the heaviest breeds, typically weighing between 64–120kg. This puts them in the giant dog bracket.

Male Saint Bernards tend to be larger than females, generally weighing toward the upper end of that range. Females are typically lighter and slightly shorter. Individual variation within the breed is normal — genetics, diet, and health all play a role.

When do Saint Bernards stop growing?

Saint Bernards reach their full adult height fairly quickly, but continue to fill out in muscle and bulk after that. As a giant breed, Saint Bernards are among the slowest to mature — expect them to reach full adult size at around 18–24 months. They may look adult-sized well before that, but their bones, joints, and musculature take longer to fully develop. Avoid over-exercising giant breed puppies before they're fully grown — it can damage developing joints.

Is a Saint Bernard the right size for me?

Size matters more than people realise when choosing a dog. Here's what 64–120kg means in practice:

• Everything costs more. Food, medication, anaesthesia, and even kennels are priced by weight. Giants are expensive to own.
• Space is essential — a Saint Bernard at up to 120kg needs a home with real space and ideally a garden.
• Shorter lifespan — giant breeds typically live 8–10 years. This is simply biology — maintaining such a large body accelerates ageing.
• Physical strength — at 64–120kg, a Saint Bernard pulling on a lead is serious. Leash training from puppyhood is non-negotiable.

How do I keep my Saint Bernard at a healthy weight?

The target range for an adult Saint Bernard is 64–120kg. A simple check: you should be able to feel their ribs without pressing hard, but you shouldn't be able to see them. Viewed from above, there should be a visible waist.

Obesity is the most preventable health problem across all dog breeds — and Saint Bernards are particularly prone to weight gain. Measure food portions rather than estimating, limit treats to 10% of daily calories, and factor in daily exercise as part of their routine.

If you're unsure whether your Saint Bernard is a healthy weight, ask your vet at their next annual check-up. Most practices offer free nurse weight clinics.