According to various sources, the largest dog breeds are:

1. Mastiff
2. Boerboel
3. Tosa Inu
4. Saint Bernard
5. Great Dane
6. Leonberger
7. Neapolitan Mastiff
8. Newfoundland
9. Anatolian Shepherd
10. Tibetan Mastiff
11. Rottweiler
12. Bullmastiff
13. Akita
14. Black Russian Terrier
15. Irish Wolfhound
16. Great Pyrenees
17. Dogue de Bordeaux
18. Bernese Mountain Dog
19. Scottish Deerhound
20. Cane Corso

The English Mastiff is considered the worlds biggest dog breed by weight, with some individuals weighing as much as 200 pounds. However, the Great Dane holds the Guinness World Record for the tallest dog ever recorded, with a height of 44 inches.