>Hi Cetin,
>if I true understand when Char type or another fields lengths is big and count is many , its same with 1st situation. i am right ?

I didn't understand what you mean. What I'm saying is if say:
5 columns all c(10) - 300000 recs = ((5*10)+1)*300000+headersize
15 columns all c(10) - 100000 recs = ((15*10)+1)*100000+headersize

they don't both have the same size. 1st one would be bigger (if reccount is small enough to compensate difference in headersize).

PS: In your original question numbers were different? I might have missed that.
Cetin