measuring flour by weight

weigh out your flour by first measuring by cup, then weigh the contents of your cup. do this several times, and get your average weight for your kitchen. Do this for all ingredients, take your own notes.
Types, manufacturers of flour vary in weight by volume.
Recipes are written in cups for the small volume and home cook as it is a basic method of measurment in the US.

Many recipes will list cups, oz and grams.

I am a fan of re writing your formulas with your notes to insure it works for you.

Yes to everything m. brown said.

Just to add:

The differences in weight and volumes according to various sources is the reason weight -- which reflects the actual amount of flour better, is the preferred method. However, weight alone is not entirely consistent but varies slightly with humidity. The ultimate lesson for the home baker is not immediately obvious. It must be understood that all quantities going into the dough are somewhat inexact. Most of all, flour, liquid, and yeast.

Baking in small quantities, i.e., less than a dozen loaves at a time, affords the luxury of adjusting quantities on the fly. If for no other reason than the baker can see the bottom of the bowl and whether all the dry are picked up or whether the dough mass sticks to the bowl. Bread dough is sticky. Ultimately, it shows more desire to stick to itself than anything else. When first mixed, it will just barely clear the bowl. When kneading is ultimately completed (windowpane stage), it will clear the board and the baker's hands but still feel tacky. The baker depends on sight and feel to make the determination. Sight is more important in the early stages, feel in the latter. The baker adjusts liquid and flour amounts during the process to match these simple criteria.

Some doughs don't fit within the normal "feel" range; and must be made very stiff or very soft. Ultra-stiff doughs are uncommon for reasons that become tragically obvious the first time you make one accidentally. Soft doughs are more common, particularly with sweet breads. For those breads which deviate from the norm, the recipes will reflect their special natures and you'll have to adjust your "feel" expectations accordingly.

FWIW, most but not all good bakers find it easier to short the flour slightly in the first mix, then add flour as necessary to make the dough. There's a basic proportionality to which most bread doughs come pretty close. That is: For every 3 volumes of dry ingredients, 1-1/4 to 1-1/2 volumes of liquid. So, if a recipe calls for 6 cups (700 gms) of flour, they'll start with 5 cups or 600 gms and all of the liquid suggested, then add flour as necessary during the first mixing stage. Depending on the bread, I might short liquid rather than flour. My recipes reflect that.

Yeast is inconsistent, and yeast activity is measured in changes in volume rather than precise initial measurement by weight or volume, or in time allowed for rising. This means that if you end up adding flour to a recipe and changing the yeast/flour ration such that you've got slightly less than the ideal amount of yeast, the yeast's natural reproduction and metabolism will eventually catch up -- you simply substitute time for amount. If there's slightly too much, you'll punch down sooner; and if the yeast is going very fast, you'll add an extra rise to make sure the yeast's metabolism is at the right stage when it goes into the oven.

Go ahead and use your scale, it will help make your initial measurements closer and more consistent. But ultimately, you can't substitute measurement for observation and touch. To bake well, you've simply got to pay attention. And that's the lesson.

BDL

Yes, to everything Boar-d-Laze says---which has got to be a first.

Just to round out his suggestions with a couple of thoughts.

Professional bakers work on formulas, rather than recipes, in which there is a proportionate amount of liquid to other ingredients. That's why weight measurement makes more sense for them. Unlike making a couple of loaves at home, it's rather difficult to adjust the dough for, say, a hundred loaves by adding a little more flour or a little more liquid.

For the home baker, however, you may notice that either way, the recipe always says to add more flour or more liquid to achieve the desired feel. In short, the goal should be, as BDL says, to develop the right consistency of the dough. That only comes from experience.

I happen to work with weight, because I use a lot of European cookbooks, and that's how their recipes are written. And most modern American writers, like Peter Reinhart, also use weight (Peter nicely gives both, btw). I question, however, whether it really matters to the home cook. For years I followed recipes slavishly, and always got a decent loaf. Now that I'm beginning to understand bread making (I figure, oh, maybe another 20 years of baking every week and I'll be there) I understand why weight is preferred. But for a couple of loaves it just doesn't really matter.

What has to be stressed is that the dough lets you know when it's right. Which, of course, is what BDL says right along.

I do think if I was making as many as 12 loaves at a time, though, I would go with weights and strive for the correct proportion. Using volume measurements, I don't think I'd attempt more than 4 loaves at a time.

And, while I can't demonstrate this with numbers, my gut feeling is that volume measurement works better if you're baking actual loaves in a pan. But for free-shaped loaves, weight probably works better as a starting point---particularly if you're into delayed fermentation, pre-ferments, and so forth.

FWIW, every authority seems to have a different figure as to what a cup of flour weighs on average. But you'd hardly go wrong using 4.5 ounces as a starting point.

I would also suggest that any novice baker who doesn't own a copy of The Bread Bakers Apprentice is doing themself a disservice.

Thank you, thank you, boar-d-laze
I've been trying to tell people this for a long time. In a bakery you have to be more precise, each error is magnified many times. At home, no.
Doesn;t it tell us something that each cookbook gives the conversion of flour from volume to weight as different? If the cookbooks have such a range of error, i think we're ok to be more approximate. If the recipe is in cups, then for heaven's sake use cups!

Yes to what everyone has said, especially the part Siduri said about the 'margin-of-error' in cookbooks.


On a side note:
Yes and no. I tend to measure my flour by the 50lb bag. A couple cups off here and there won't make much difference to me. ;)