I am not quite sure what you mean by ... "kit" (a 18-55 kit)? But if you mean (only) an additional, single 18-55 lens then I can say: Yes, it will store all those items in the larger compartment together, a lens of 6.2 inches included. (Then you will still have room in the compartment on top for single smaller items.) The storage room of this bag is not too large and not at all too small. It is very practical, well thought through, and with the dividers you can very well protect each item from the other.