Arrm length

How do I measure the arm length with a “drop shoulder”? The sleeve ends with 48cm., I need the sleeve length to be approximately 70cm. How do I measure this with the drop shoulder?
Thanks, edith

I don’t know of a general recommendation for this but I can tell you what I do.
Finish the body of the sweater, front and back if possible and add the collar or neckband. That ensures that the sweater will fit as it will when complete. Try it on and note where the shoulder falls on your upper arm. You can then measure from that point down to the wrist and have a better idea of the sleeve length.

Thanks, this is a little like what I thought, otherwise, let my husband
put it on & try to figue out where the houlder ends…the pattern is for a
very larger man…