If you’ve just brought home a Sussex Spaniel 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 Sussex Spaniel is a medium-sized breed. Adult males typically weigh 35–45 lb (15.9–20.4 kg) and females 35–45 lb (15.9–20.4 kg). Most Sussex Spaniels reach about half their adult weight around 4.3 months, hit 90% by roughly 9.1 months, and are fully grown near 13 months. A useful rule of thumb for medium breeds: they roughly double their four-month weight.
When do Sussex Spaniels stop growing?
Most Sussex Spaniels reach their full adult height and weight by about 13 months. Growth is fastest before 4.3 months, then slows steadily — by 9.1 months your puppy will be about 90% of its final size.
How much should a Sussex Spaniel puppy weigh at 4 months?
A typical 4-month-old Sussex Spaniel weighs roughly 16–21 lb, about 46% of its adult weight. Use the calculator above with your puppy’s exact weight for a personalized estimate — individual dogs vary.