Sorry, there should be quotations around Sheet2, i.e.
=vlookup(D6,'Sheet2'!$A$1:$B$3,2,false)

"Melissa" wrote:

In F8:
vlookup(D6,Sheet2!$A$1:$b$3,2,false)

"paulh" wrote:

sheet 1
type in to sheet1 d6 (15gr) refer to sheet2 and result in f8 sheet1 to be 3.5
or type in 10gr into d6 sheet 1 and result in f8 sheet 1 to be 2.7

Sheet2
A B
10GR 2.7
15GR 3.5
20GR 5.6