According to weight measurement 1kg = 2.205 lb then 12oz = 1000gm/2.205/16*12=340.14 gm, if the liquid is water (1gm water is 1 ml in capacity) then 12oz water = 340.14 ml.
But according to British capacity measure 1 fluid oz = 0.0284 litre
thn 12 fluid oz = 12* 0.0284*1000ml=340.8ml
And, the American liquid
So, you have to clarify that what kind of liquid, and/or what kind of system you are using. I hope this may help you.
2008-05-27 17:05:25 補充:
Sorry incomplete ...
And the American capacity: 1 pint=16 liquid oz=0.473 litre then 12 oz =0.473*12/16*1000ml=354.75ml