A frequently repeated leitmotif in the Foundation stories is that Empire's stuff is colossal: a colossal expanse, colossal urbanized planets, colossal nuclear generators, colossal war fleets composed of colossal spaceships. Instead, it is often implied that the Foundation's technology is miniaturized, like its power units and force fields.

Is also implied that Foundation's spacecraft are relatively small. Not only because of the miniaturization but because during the collapse of the Empire in the peripheral areas the scattered successor political units of the Empire, e.g. Terminus, the Four Kingdoms or Askone, had to improvise with small ships for civilian use.

But I don't recall at any point a clear figure expressing the size of a spaceship, of any of the types that appear in the story.

In many passages of Foundation very small ships appear, equivalent to a pleasure yacht, for the use of at most four or five people, such as those used by Bayta Darell in the story of the Mule or the one used by Arkady Darell to escape from Terminus at the beginning of her involvement with the Second Foundation.

In other passages it is implied that there are larger spaceships, with crews of dozens of people, like that trader ship in which Hober Mallow arrives on Korell in which he has to communicate with parts of his crew remotely. But in that same story a few pages later a hostile encounter between a similar Foundation ship and an Empire warship is described and the massive size difference is abundantly clear.

One gets the impression that it is a difference comparable to the famous opening scene of Star Wars Episode IV where Princess Leia's ship is intercepted by a star destroyer.

But, impressions aside, what is the typical size of a Foundation pleasure ship, a Foundation commercial ship, and an Imperial warship, expressed in meters or metric tons?

Is there any clear figure in the materials written by Isaac Asimov or in any source that can be considered canon?

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    It's an interesting question. But I think Asimov deliberately kept some aspects of technology vague in his stories in order to make them more timeless. It's easy to make a story sound anachronistic if you get too specific, e.g., by having characters rely on paper calculations instead of computers (Heinlein), smoke cigarettes on spaceships (Asimov), or feel utterly helpless in the absence of a male protector (Levin). Arthur Clarke and Cordwainer Smith managed to avoid most anachronisms in their work by never explaining how their technology worked. Aug 8, 2021 at 23:47
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    My recollection is that the books consist mostly of dialog. In conversation, it's not really natural for someone to say, "Here we are aboard this 12.7 km starship."
    – user2490
    Aug 9, 2021 at 13:52

1 Answer 1


I've looked up "mile", "meter", "feet", "ship" in the original trilogy and in Foundation's Edge, the first novel published afterwards.

The only quote in Foundation's Edge that alludes to the size of spaceships is this:

The old Imperial Navy had ships five hundred meters long with no more living space than would fit in a small apartment.

(Chapter 4.1)

The only quote in the original trilogy with this kind of data is this:

With quick practiced motions, he moved the small levers that opened all communications, so that every part of the two-mile-long ship was within range of his voice and image.

Book 1 - Foundation. Part III The Mayors - Chapter 7.

This refers to an Imperial Cruiser found by the Kingdom of Anacreon and repaired by Foundation technicians.

So we must deduce that ordinary Imperial spaceships with a crew of a dozen people were about 500 meters long and the more massive Imperial Cruisers were at least 2 miles long (about 3,200 meters).

From this we can also deduce that a Foundation spaceship with a dozen crew is substantially smaller than 500 meters.

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