I've often wondered how I can be sure I've eaten a KeZayith of flour when I eat something small but complete - like one cookie - and struggle with the decision of whether or not to eat more in order to be sure I need a Berachah, or whether to rely on the Safeik and not make one.

It just occurred to me that (at least in the U.S.) food labels can be a guide to help in this process. If it were possible to break down the caloric value of a KeZayith, it might then be possible to figure out, from the labeling, how much flour is in the food item.

For example, there are 3.87 calories in a gram of white sugar, and according to many sources available online, the standard sugar content for commercially prepared cookies is 24.73 grams per 100 grams. A similar calculation should be available for oil/margarine, etc., this despite the fact that all products are proprietary and recipes vary, because the fat content and sugar content (as well as fiber, protein, and others) are displayed on the side panel of the packaging.

It should be possible, then, to determine by process of elimination the maximum amount of flour contained in a serving based on these calculations. Then it's a simple game of division to determine, from the information on the panel, how many cookies (or other food products) are in a serving, and divide by that number.

Personal note: I'm a liberal arts guy. Even if I sat down with a paper and pencil and started doing all the calculations myself with the amazing math skills I acquired in high school (since I avoided math in college), I wouldn't assume I had factored all the variables or even come up with the correct calculations. Can anyone shed some light? There might even be a resource from the USDA or somewhere that already has this information broken down into digestible (no pun intended) nuggets.

  • 3
    This wouldn't work. Kezayis is a measure of volume, but the calorie value does not tell you anything about the density of the final product. Furthermore, I am strongly suspicious of the claim that there is a "standard" sugar content in commercially prepared cookies (precise to 2 decimal places!). Just adding a few chocolate chips or some topping would throw that off completely.
    – Dave
    Jan 15, 2013 at 18:16
  • I agree with that the margins of error here would make this technique pretty useless.
    – Double AA
    Jan 15, 2013 at 18:31
  • @Dave, I thought so, too, but the panel lists all the sugar in the product by gram, chocolate or not, so you should be able to isolate it enough to come up with an average for the product, shouldn't you?
    – Seth J
    Jan 15, 2013 at 18:53
  • @DoubleAA is this on topic?
    – mevaqesh
    Aug 1, 2016 at 21:23

1 Answer 1


assuming that a kezayit is 25.6 grams (as per http://www.chabad.org/search/keyword_cdo/kid/10951/jewish/Kezayit.htm) and that in all purpose white flour, there are 100 calories in 30 grams (http://caloriecount.about.com/calories-gold-medal-all-purpose-flour-i116037) there are, then, about 86 calories in a kezayit (I'm liberal arts also so my math is inexact).

The question is how much flour is there in a particular cookie. For that I would assume you look at a serving size and determine the volume of that one cookie and then work on percentages of the different things contributing calories.


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