If you’ve just brought home a Irish Water 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 Irish Water Spaniel is a large breed. Adult males typically weigh 55–68 lb (24.9–30.8 kg) and females 45–58 lb (20.4–26.3 kg). Most Irish Water Spaniels reach about half their adult weight around 4.5 months, hit 90% by roughly 9.9 months, and are fully grown near 16 months. Large breeds keep growing well past their first birthday, mostly filling out in the chest.
When do Irish Water Spaniels stop growing?
Most Irish Water Spaniels reach their full adult height and weight by about 16 months. Growth is fastest before 4.5 months, then slows steadily — by 9.9 months your puppy will be about 90% of its final size.
How much should a Irish Water Spaniel puppy weigh at 4 months?
A typical 4-month-old Irish Water Spaniel weighs roughly 22–28 lb, about 44% of its adult weight. Use the calculator above with your puppy’s exact weight for a personalized estimate — individual dogs vary.