When the Huffington Post published a pictorial on 15 "Insanely Enormous Dogs," mastiffs and Newfoundlands both made the list. The breeds are known for their size, so it isn't surprising to see pictures of the dogs dwarfing humans and other canines. Either breed brings words like "mammoth" and "gigantic" to mind, so it's interesting to note how mastiffs and Newfoundlands compare in size.
The Mastiff's a Little Taller
Both mastiffs and Newfoundlands are tall pooches, but the mastiffs have the "Newfies" beat by a couple of inches. The American Kennel Club standard for Newfoundlands says a male of the breed should stand 28 inches tall at the shoulder and a female 26 inches. The breed standard for mastiffs set by the AKC requires that a female be at least 27½ inches and a male be 30 inches, minimum. Potential mastiff parents should notice that the standard says those are the "minimum" heights -- meaning it's not unusual to see bigger specimens.
Mastiffs Have More Mass
The AKC doesn't always list weight minimums for recognized breeds, and that's the case with mastiffs. It does, however, list the weight range for the Newfoundland breed to be 100 to 120 pounds for females and 130 to 150 pounds for males. There are different types of mastiff breeds, though, so if you look at the standard for the Neapolitan mastiff, for example, you'll see that there is a weight range listed: 110 to 150 pounds, depending on whether you're weighing a male or female dog. Additionally, mastiff breeders say that males can weigh between 160 and 230 pounds, and even the females, weighing in at 120 to 190 pounds, can dwarf male Newfoundlands.
Magnitude of the Muzzle
The mastiff pretty much has the Newfoundland beat in size in almost every area but the muzzle. The AKC describes the standard for a mastiff's muzzle to be short, blunt and square. It's not quite the short snout of a bulldog, but it's noticeably shorter than the Newfie's nose, which is typically as long as it is deep and not as squared-off.
A Possible Connection
The Newfoundland breed may owe at least part of its giant heritage to the mastiff breed. Both the American Kennel Club and the PetMD website say that the origins of the breed are unclear, but PetMD says it's commonly presumed that the Newfoundland breed got its start with Tibetan mastiffs.