So a basic bread recipe might look like (off top of head, not sure if these amounts make any sense)

100 Bread Flour
 30 Water
  1 oil

I know the flour is in weight ounces, but often times in side-by-side recipes I see the water converted into fluid ounces (8 ounces of water equaling 1c). I know sometimes it just so happens that they're the same, but with water that is not so. 1 fl oz water ~= 1.05 av oz water. Close, but off by near 1/2 oz by the time you add 8 of them.

So which do bakers use with fluids? Do they use av or fl? Should I expect to be able to weigh my fluids along with everything else or do I need to convert to fl?

2 Answers 2


If specific units are not given (i.e. you just have a ratio), then you should always go by weight, not volume.

Everything that happens in baking, every chemical reaction, is based on the actual number of molecules of a particular ingredient, which corresponds to its weight. Volume is simply a rough approximation used in many home cooking/baking recipes.

Note that if using metric measurements (g or mL) then the weight vs. volume measurements actually are the same for water. So consider using metric for baking, if you can, because that way the conversions are much easier and you can measure out your liquids in a measuring cup without having to do any conversion math.

  • 3
    +1 for mentioning the obvious of the metric system, maybe one day the fine inhabitants of the USA can see this. Mixing the two is bad form as NASA well knows. Remember water is gm = ml at sea level, at high altitude it's lighter per volume and it boils faster :-)
    – TFD
    Commented Feb 21, 2011 at 21:00
  • @TFD Hardly anyone lives at sea level. Metric not much help there. Commented Feb 21, 2011 at 21:29
  • @CrazyEddie: My answer wasn't actually meant to be a knock against the imperial system (I've got plenty of recipes using ounces, cups, etc.) but merely some practical advice; although TFD is essentially correct about the sea level thing, it's realy more the boiling point you need to worry about. The actual density of water does change, but the changes are so subtle that you can essentially ignore them. If you're cooking at very high altitude then you've got more important things to worry about, like the effects of leavening agents and moisture loss.
    – Aaronut
    Commented Feb 22, 2011 at 3:26
  • @CrazyEddie, @Aaronut It was a joke, hence the smiley thing :-)
    – TFD
    Commented Feb 22, 2011 at 8:20
  • Thanks for clarifying, @TFD - I did get that, and my response was for his benefit because I think he read a little too far into the sea level comment.
    – Aaronut
    Commented Feb 22, 2011 at 15:20

Baker's ratios are (a) always given by weight (b) relative to the total amount of flour (which is 100). An example is a “standard” 60-2-2 French loaf: 100% flour (implied), 60% water, 2% salt, 2% (fresh) yeast. To make a 1 lb french loaf, you'd use 1lb / 1.64 = 9¾ oz flour, 9¾ oz × 0.6 = 5⅞ oz water, and slightly less than 9¾ oz × 0.02 = ¼ oz each salt and fresh yeast. Doing the math in Metric is obviously much easier (and how I personally do it).

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