If you’ve just brought home a Saint Bernard puppy, the calculator below estimates its adult size from its current weight — personalized to your dog, not just a breed average.
Estimates combine your puppy’s current trajectory with typical growth curves for this breed and size class. Individual dogs vary — nutrition, genetics and neuter timing all matter. For health concerns, ask your vet.
The Saint Bernard is a giant breed. Adult males typically weigh 140–180 lb (63.5–81.6 kg) and females 120–140 lb (54.4–63.5 kg). Most Saint Bernards reach about half their adult weight around 5.0 months, hit 90% by roughly 12.2 months, and are fully grown near 20 months. Giant breeds grow longer than any other dogs — some don’t reach full size until age two.
When do Saint Bernards stop growing?
Most Saint Bernards reach their full adult height and weight by about 20 months. Growth is fastest before 5.0 months, then slows steadily — by 12.2 months your puppy will be about 90% of its final size.
How much should a Saint Bernard puppy weigh at 4 months?
A typical 4-month-old Saint Bernard weighs roughly 53–65 lb, about 41% of its adult weight. Use the calculator above with your puppy’s exact weight for a personalized estimate — individual dogs vary.