What Sized Joists for 9x13 Shed Floor Framing?

[Diyer321]

Hello i am going to be building a 9x13 shed on concrete blocks and would like some advice on what size joists to use.

I want to have 6 piers, 1 in each corner and 1 on each side in the middle of the 4m length.

I havent decided how far apart to space the joists or how to attach them but i am trying to keep the costs as low as possible (while only having 6 piers) and i will cover the floor with 18mm osb3.

I think the span between piers will be about 8ft and 6ft.

I already have some 3x2's and 4x2's for the walls, cladding and fibre cement roof sheets.

Thanks in advance

[Diyer321]

I should of mentioned i plan to hav the joists running the 9ft length of the shed and im going to make the concrete blocks myself so they will be 60cm square and 6 inch thick.

Thanks