The Importance of the Passenger Space Ratio
When you board a cruise ship, one of the crucial factors affecting your enjoyment while onboard is how spacious the vessel feels. As you're likely going to be there for a while, you will have a view on how much personal space you enjoy. Some folks call this 'elbow room'.
To help you choose, there are specific ratios that can guide your final decision of cruise line and cruise ship. The Passenger Space ratio is the one that highlights explicitly how much space you may expect. It is a simple ratio that relates the total volume of the ship to the number of passengers. In simple terms, it translates into how much space you can expect onboard?
By definition, gross tonnage is the measurement of a ship's internal volume, its overall interior space. The new Gross Tonnage calculation for ships determines rules and regulations, registration fees and port dues, as well as, and most importantly, to the cruise experience, the amount of passenger space available. If you are interested in finding out more information on this subject, it is worth reading the Berlitz Guide to Cruising. We use it all the time and you can read our review. Click to read our review.
Defintion of Tonnage GT vs GRT
Gross Tonnage (GT) is a measure of a ship's total enclosed volume — not its weight. It was introduced by the International Maritime Organization's International Convention on Tonnage Measurement of Ships, adopted in 1969 and brought into force on 18 July 1982. GT replaced the older Gross Register Tonnage (GRT), which had been used since the 19th century and measured only certain enclosed spaces using a simpler cubic-feet formula.
Older ships were given a transition period and had to convert fully to GT by 1994, so virtually every cruise ship sailing today — including all the ships in our worksheet below — is measured in GT, not GRT.
GT is calculated using a formula based on the ship's total enclosed volume (V, measured in cubic metres):
GT = K₁ × V
K₁ is a sliding logarithmic factor that increases slightly as the ship's volume increases, which is why GT doesn't scale in a simple straight line with size. The exact formula is set out in Annex I of the 1969 Tonnage Convention.
GT determines a ship's manning regulations, safety requirements, registration fees, and port dues — and, most usefully for passengers, it's the figure that lets us calculate the Passenger Space Ratio.
If you look up a ship's tonnage yourself, make sure you're using Gross Tonnage (GT) — this is the figure quoted on cruise line spec sheets, Wikipedia ship infoboxes, and class society registries. You may occasionally see GRT used in older historical references or for vessels built before the 1990s, but for any current cruise ship GT is the correct and only figure to use.
How the Passenger Space Ratio is Calculated
By definition, gross tonnage is the measurement of a ship's internal volume, that is, its overall interior space.
The measurement is, broadly, the capacity in cubic feet of the spaces within the hull and of the enclosed spaces above the deck available for cargo, stores, passengers and crew, with certain exceptions, divided by 100. Thus 100 cubic feet of capacity is equivalent to one gross ton.
It is easy to calculate and get a feel for how crowded you might feel on a particular class of ship. It is the simple ratio between the size of the vessel Gross Tonnage divided by the number of passengers. Gross Tonnage (GT) is the number used for all ships built after 18th July 1982.
The resulting magic number is called the Passenger to Space Ratio.
The Formula
Passenger Space Ratio = Gross Tonnage (GT) divided by the number of passengers
The simplicity makes it is easy to compare cruise ship space ratios since these two numbers are freely available. In this way, you can easily compare like with like. Our chart below shows all the essential cruise ship ratios you need.
If we look at the actual numbers involved, Gross Tonnage is a bit of a mathematical puzzle and doesn't have anything to do with the weight of a ship. It is a measure of all of the enclosed spaces within the vessel. All you need to know is that it is a "fair" number that achieves a method of representing all ships of different sizes accurately.
As you don't usually know how many passengers will be on any given cruise ahead of time, a standard number is applied. Often, this is the number of staterooms with two occupants in each, sometimes known as the ship's capacity or double occupancy.
Calculating the Ratio
Finally, we can calculate the Passenger Space Ratio. It is merely the amount of space on the ship divided by the number of passengers.
Our table below shows the gross tonnage, number of passengers (double occupancy) and the calculated passenger space ratio for a selection of our favourite cruise lines.
Once you have a Ratio, you can then start to compare ships. Many will fall within a reasonably close range, and some ship design features will affect this number.
If you plan to look up the Gross Tonnage (GT) for yourself, be sure to use the Gross Registered Tonnage (GT) and not one of the other similar numbers. These include Net Register Tonnage, Displacement, Compensated Gross Tonnage, etc.
Remember that there are several other ratios and statistics that you can use to gauge your possible cruise experience. The Crew to Passenger Ratio is one such ratio. Taken together, these can help to give an improved perspective on what you can expect on your cruise.
As a rough guide, the Passenger-to-space Ratio bands are as follows:
- 51 and Above - Very Spacious Ships
- 31-50 - Spacious
- 21-30 - Not so spacious
- 20 and under - Expect cramped conditions
Try it Yourself - Our Free Calculator
Want to check a ship that isn't in our worksheet below? Plug in its Gross Tonnage and double-occupancy passenger count to get its Passenger Space Ratio — add crew size too, and you'll get its Crew-to-Passenger Ratio at the same time.
Passenger Space Ratio Calculator
Enter a ship's Gross Tonnage, passenger count, and crew size to see both ratios.
Cruise Ship Ratios Worksheet
The table below lets you compare the Passenger Space Ratio across more than 30 ships from the luxury and premium cruise lines we cover most often, alongside their Gross Tonnage, passenger capacity (double occupancy), crew size, and Crew-to-Passenger Ratio. Gross Tonnage is measured in GT (a measure of enclosed volume, not weight), and both ratios are calculated using the formulas above — so you can check our maths, or use the same figures to work out the ratio for any ship not yet listed here. Scan down the Passenger-Space Ratio column to quickly spot which ships fall into the "very spacious," "spacious," and more crowded bands described earlier.
| Ship | Cruise Line | Gross Tonnage (GT) | Passengers (Double Occ.) | Crew | Crew-to-Passenger Ratio | Passenger Space Ratio (PSR) |
|---|---|---|---|---|---|---|
| Queen Anne | Cunard | 113,000 | 3000 | 1050 | 2.86 | 37.67 |
| Queen Elizabeth | Cunard | 90,901 | 2503 | 900 | 2.80 | 36.3 |
| Queen Mary 2 | Cunard | 148,530 | 2620 | 1254 | 2.10 | 56.7 |
| Queen Victoria | Cunard | 90,049 | 2061 | 981 | 2.10 | 43.7 |
| Mitsui Ocean Fuji | Mitsui Ocean Cruises | 32,000 | 450 | 330 | 1.30 | 71.1 |
| MSC Seaside | MSC | 153,156 | 5331 | 1413 | 3.80 | 28.7 |
| Oceania Vista | Oceania Cruises | 67,000 | 1200 | 700 | 1.71 | 55.8 |
| SeaDream I | SeaDream | 4,253 | 112 | 95 | 1.18 | 37.9 |
| SeaDream II | SeaDream | 4,333 | 112 | 95 | 1.18 | 38.7 |
| Seabourn Quest | Seabourn | 32,000 | 450 | 300 | 1.30 | 71.1 |
| Seabourn Encore | Seabourn | 40,350 | 604 | 450 | 1.30 | 66.8 |
| Seabourn Ovation | Seabourn | 40,350 | 604 | 450 | 1.30 | 66.8 |
| Seabourn Pursuit | Seabourn | 23000 | 264 | 120 | 2.20 | 87.12 |
| Seabourn Venture | Seabourn | 23,000 | 264 | 120 | 2.20 | 87.12 |
| Seven Seas Explorer | Regent | 55,254 | 732 | 567 | 1.29 | 75.48 |
| Seven Seas Grandeur | Regent | 55,254 | 750 | 552 | 1.36 | 73.7 |
| Seven Seas Mariner | Regent | 48,075 | 708 | 445 | 1.60 | 67.91 |
| Seven Seas Navigator | Regent | 28,550 | 490 | 325 | 1.51 | 58.27 |
| Seven Seas Splendor | Regent | 55,254 | 750 | 542 | 1.39 | 73.7 |
| Seven Seas Voyager | Regent | 42,363 | 708 | 445 | 1.60 | 59.84 |
| Silver Cloud | Silversea | 16,927 | 260 | 208 | 1.25 | 65.1 |
| Silver Discoverer | Silversea | 5,218 | 124 | 96 | 1.29 | 42.0 |
| Silver Explorer | Silversea | 6,072 | 144 | 117 | 1.23 | 42.1 |
| Silver Origin | Silversea | 5800 | 102 | 90 | 1.14 | 56.87 |
| Silver Moon | Silversea | 40,700 | 596 | 411 | 1.45 | 68.3 |
| Silver Muse | Silversea | 40,700 | 596 | 411 | 1.45 | 68.3 |
| Silver Shadow | Silversea | 28,258 | 388 | 303 | 1.28 | 72.83 |
| Silver Spirit | Silversea | 39,519 | 608 | 411 | 1.48 | 65.0 |
| Silver Whisper | Silversea | 28,258 | 388 | 302 | 1.29 | 72.83 |
| Silver Wind | Silversea | 17,400 | 302 | 222 | 1.36 | 57.62 |
| Star Breeze | Windstar | 9,975 | 212 | 153 | 1.38 | 47.1 |
| Star Legend | Windstar | 9,975 | 212 | 153 | 1.38 | 47.1 |
| Star Pride | Windstar | 9,975 | 212 | 153 | 1.38 | 47.1 |
| Wind Spirit | Windstar | 5,350 | 148 | 88 | 1.69 | 36.15 |
| Wind Star | Windstar | 5,350 | 148 | 88 | 1.69 | 36.15 |
| Wind Surf | Windstar | 14,745 | 312 | 163 | 1.92 | 47.26 |
| Wonder of the Seas | Royal Caribbean | 236,857 | 6988 | 2300 | 3.03 | 33.89 |
FREQUENTLY ASKED QUESTIONS
Passenger Space Ratio FAQs
Our readers' most-asked questions about the Passenger Space Ratio (PSR)— answered honestly, based on first-hand experience and extensive research.
What is a good Passenger Space Ratio for a cruise ship?
Generally, a PSR of 31 or above is considered spacious, and anything above 51 is considered very spacious. Most luxury and ultra-luxury lines — Seabourn, Silversea, Regent, and Oceania among them — sit comfortably in the 55-75+ range, which is one of the reasons they feel noticeably less crowded than mainstream ships.
What is the highest Passenger Space Ratio cruise ship?
Among the ships in our worksheet, Seabourn Pursuit and Seabourn Venture lead with a PSR of around 87, followed closely by several Seabourn, Regent, and Silversea ships in the 65-75 range. Expedition-style luxury ships with low passenger counts tend to top this list.
Is a higher Passenger Space Ratio always better?
Not necessarily. PSR tells you how much enclosed volume exists per passenger, but it doesn't tell you how that space is allocated. A ship with a high PSR but a large proportion of that volume given over to crew areas, machinery spaces, or vast atriums may not feel as personally spacious as a slightly lower-PSR ship with generously sized cabins and uncrowded public rooms. Use PSR as one data point alongside cabin size, public deck space, and your own experience reports.
How is Passenger Space Ratio different from the Crew-to-Passenger Ratio?
PSR measures physical space per passenger (Gross Tonnage ÷ passengers). The Crew-to-Passenger Ratio measures service level — how many passengers each crew member is, on average, looking after (passengers ÷ crew). A ship can score well on one and only moderately on the other, so it's worth checking both. See our full guide to the Crew-to-Passenger Ratio.
Where can I find a ship's Gross Tonnage?
Gross Tonnage is published by every major cruise line on their ship spec/fact sheets, and is also listed in independent references like Wikipedia and class society registries (such as Lloyd's Register or DNV). Always check that the figure is labelled GT (Gross Tonnage), not GRT, displacement, or net tonnage, as these are different measurements entirely.
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