StarFish base plates are all 248 mm in diameter. This is normally the width of the system, as almost all MonoBlocks also have a diameter of 248 mm, and the PolyBlocks additionally give this diameter.
The exception is the RR95125 MonoBlock for 3 x 500 ml Flasks, which is slightly larger, at 262 mm, so this would be the width.
If you install the optional RR95100 StarFish Base Plate Handles, the width increases to about 375 mm.
The depth of the StarFish system will depend on the hotplate used. The approximate depth when using a Carousel Stirring Hotplate is around 310 mm, or 320 mm if using the 3 x 500 ml MonoBlock.