How big would a 1/700 scale I-400 be?Tamiya is offering one for a mere $95.00.
About 6" long…
The I400 was 400 feet long, that would make a 1:700 scale model a bit over 6 inches long.
You may have seen a typo at 1:700. Tamiya makes a 1:350 scale model of the I400. The MSRP is in the 80 to 90 dollar price range. I’ve seen it listed for sale in the 50 to 60 dollar range.
Yup.FSM Magazine has it listed under 1/700.The box cover says 1/350.
I’ve got the kit, and it’s very nice. Here’s a picture I took of one at the Tokyo Tamiya shop this past summer. Someone did some very fine detailing. I hope mine turns out as good.

Even 1/350 is too small a scale for a WWII era submarine, even a huge one for the era like the I-400.