Giant breed

Mastiff age in human years

Mastiffs are a giant breed. Here is the full age chart and what each stage means.

Updated October 2026Numbers calculated for this page

Mastiffs are a giant breed (typically 120–230 lb), so they age about 7 human years for every dog year after age two. A 5-year-old Mastiff is about 45 in human years, and the senior years usually start around age 6.

6–10 yrstypical life expectancy

80human years at age 10

~6senior years begin

120–230 lbtypical adult weight

Mastiff age chart

Dog age	Human years	Life stage
1 year	15	Young adult
2 years	24	Young adult
3 years	31	Mature adult
4 years	38	Mature adult
5 years	45	Mature adult
6 years	52	Senior
7 years	59	Senior
8 years	66	Senior
9 years	73	Golden years
10 years	80	Golden years
11 years	87	Golden years
12 years	94	Golden years

Uses the common size-based chart: the first year equals about 15 human years, the second adds about 9, and each year after that adds 4 (small), 5 (medium), 6 (large) or 7 (giant). It is an estimate, not a medical measure.

What each stage means for a Mastiff

Young adult (1–3): still learning. Keep training consistent and set the healthy weight now; for a Mastiff that is usually within 120–230 lb.
Mature adult (3–5): yearly checkups, dental care and steady exercise. Watch the waistline as activity drops.
Senior (6+): many vets suggest checkups every six months, plus attention to joints, teeth and weight changes.

How much a Mastiff eats

A spayed or neutered adult around 175 lb needs roughly 2,980 calories a day, about 7.8 cups of a typical 380-calorie-per-cup dry food. See the full feeding guide for a 150 lb dog.

Planning the budget? See what a Mastiff costs per year.

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Other giant breeds

Rottweiler Cane Corso Great Dane Newfoundland Saint Bernard Bullmastiff Irish Wolfhound Leonberger Anatolian Shepherd Dogue de Bordeaux

Any giant dog: see how old a 7-year-old giant dog is or try the dog age calculator.

Questions people ask

How old is a 10-year-old Mastiff in human years?

About 80, using the giant-breed chart.

How long do Mastiffs live?

Typically 6 to 10 years, though genetics, weight, diet and vet care all matter.

When is a Mastiff considered a senior?

Around age 6, roughly the last quarter of the breed's typical lifespan.

The Paw Plan shares general pet care information, not veterinary advice. Figures on this page are estimates calculated from the assumptions shown. Every pet is different, so check with your vet about yours.