>I tried it with and without an 'AS'. The ehading is 'EXP1' or similar.

Never Never do this!! Unless You are surely not to use the 'exp1' again!!

e.g. Select item.itemkey, item.PackQuant, item.Length, item.width, item.height,;
item.length * item.width * item.height * item.packquant / 1000000 AS CartonSize;
from item where itemkey = ?Thisform.txtitemkey.value ;
into cursor tmpitem

grid1.controlsource = tmpitem

Reasons:
1) You need to make a meaningful word to user
2) You will got trouble when edit and save the select again, especially in View!

Anyway, You can treate the calculation field as Real Field to use but of cos
cannot write it!
no one will use coding to remember 'exp1' !!