From Fusselman.org
We're currently booked with NCL for our 2009 Egyptian Adventure, but had recently been exploring other options, specifically the Azamara Quest. The Quest is a smaller ship, which got me to thinking about ship size compared to available amenities. Obviously, the bigger a ship is, the more facilities they'll need, since a dining room, movie theater, etc, only scales so large. This yields more choices for any given passenger. Conversely, on a smaller ship, there are less total facilities and less choice. I figured out that you can take a crack at passenger density by dividing tonnage by the number of passengers, giving you a "Tons per Passenger" number. Below are some tables I've calculated for various lines classes.
Princess
| Class | Grand | Sun | Explorer |
| Example Ship | Star Princess | Caribbean Princess | Sea Princess | Pacific Princess |
| Gross Tonnage | 109,000 | 113,000 | 77,000 | 30,200 |
| Max Passengers | 2,600 | 3,100 | 1,950 | 670 / 710 |
| Tons / Passenger | 41.9 | 36.5 | 39.5 | 45.1 / 42.5 |
Carnival
| Class | Destiny |
| Example Ship | Carnival Destiny |
| Gross Tonnage | 101,500 |
| Max Passengers | 3,360 |
| Tons / Passenger | 30.2 |
Royal Caribbean
| Class | Oasis | Freedom | Voyager | Radiance | Vision | Sovereign |
| Example Ship | Oasis of the Seas | Freedom of the Seas | Mariner of the Seas | Jewel of the Seas | Enchantment of the Seas | Majesty of the Seas |
| Gross Tonnage | 223,000 | 154,500 | 138,000 | 90,100 | 81,000 | 74,000 |
| Max Passengers | 5,400 | 4,370 | 3,114 | 2,500 | 2,446 | 2,744 |
| Tons / Passenger | 41.3 | 35.4 | 44.3 | 36.0 | 33.1 | 27 |
Azamara
Azamara doesn't really have classes, as they have only two ships.
| Ship | Quest | Journey |
| Gross Tonnage | 30,300 | 30,300 |
| Max Passengers | 710 | 694 |
| Tons / Passenger | 42.7 | 43.7 |
Norwegian
Footnotes
This information was all gleaned from either Wikipedia or the cruise lines' websites.