I'd have thought 150g would be plenty. I made a scarf using 3 balls of whisper wool and it made a scarf long enough to fold in the middle and tuck the ends through the fold - do you know what I mean?

Or you could wrap it round your neck fully once or two times.
Hope this helps
:D
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OTN:-
Eyelet Cardigan using Rowan All Seasons Cotton from my stash (if I can get gauge)
Sirdar 8372 Aran Cardigan
Crochet Jumper
Monkey socks from Knitty
Up Next:-
Some socks with my beautiful yarns from Angelia
Recent WIPs:-
Sahara in Tilli Thomas Pure and Simple and Rock Star in colour Hope
My variation on the Anthropologie Capelet
A cabled hand bag for my friend (Still awaiting some bamboo handles!)