Project Hail Mary · Andy Weir, 2021
How big is the Hail Mary in Project Hail Mary?
~46m
About 46 m long as drawn here, shorter than a Boeing 747. The book doesn't give its size, so that's the map's guess.
From the bookThe map's guessReal world
Small for what it does. The rooms people live in, a dormitory, a lab and a control room stacked one above the other with the airlock on top, would fit in a two-storey house. Almost everything else is fuel: tanks of Astrophage, the microbe that is eating the Sun's light.
The deck order and the crew compartment spinning out on cables are from the book. The sizes are not. The 46 m length, the cable length and the tank layout are all the map's guesses, so use them as a feel for proportions rather than figures.
Rocky's ship, the Blip-A, is much bigger than the Hail Mary. That much the book says; its shape and size here are guesses too.
See the Hail Mary in 3D