It seems, as if the cruiser has the same dimensions as the DA, but it missing the big upper tower. I compared the DA and the cruiser via a video analysis of the final battle. With this information I scaled the existing model up and got this sizes. These suggest that the DA should be around 1km long. Only a scaled model of the Destiny Ascension from ME1 can be found in the files, but Bioware also did rough models for the ships of ME1. How was the calculation for the asari ships done? It also works just fine with the comparison picture between alliance dreadnought and cruiser that was in the The codex says that a dreadnought is around 1km long. Only two small models of the dreadnought are in the files. How was the calculation for the alliance dreadnought done? In fact in ME2 Harbinger's main hull is bigger than the one's of other reapers, because of its second hump! So Harbinger from ME2 is bigger than any other reaper! I think they did this because hey wanted to save resources (making textures for such a big model takes time). In ME2 it has a big, second hump and in ME3 they just used the sovereign model and textures without the front leg. Harbinger has two different models in ME2 and ME3. Why is Harbinger not bigger than other reapers and why are two lengths given? If a ship is missing, then either I couldn't find a model or the model was to much scaled down to work with it. It's only possible to calculate the size of the ship, if a good model of it can be found in the game files. NOTE: Sizes marked with estimated are really just assumptions. NOTE: These ship sizes are not 100% canonical! This is for everyone, who is interested in the ships of Mass Effect. Turns out, they have their actual in-game size! I was able to extract some ship models from ME 2 and 3. Here you can find the sizes of the different ship of Mass Effect.

Mass effect ship size comparison