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The title may sound silly, but the question is serious:

When I buy butter, the package says Net Wt. 16oz, and I trust this because the authorities regulate such things.

Inside the package, each stick is divided evenly into 8 tablespoons. Now, although a fluid ounce of water might weigh almost exactly a 1/16 of a lb., butter is like 80% fats. There's no way a fluid ounce of butter (exactly 2 tablespoons) weighs 1/16 of a lb.

So, how many tablespoons of butter are there in a "tablespoon" (per the package marking) of butter?

Shadow Wizard Love Zelda
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Him
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1 Answers1

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16 fluid ounces of water do not weigh one pound, they weigh a little more (about 1.05lbs), because the US fluid ounce is not based on water, unlike the liter.

You are correct that 16 weight ounces of butter aren't equivalent to 16 fluid ounces either, but they're pretty close. 1 fluid ounce of butter is 99% of one weight ounce. So if you're getting 16 weight ounces of butter, you're actually getting an extra 1% over 16 fluid ounces.

And who's going to complain about 1% extra butter?

So, your answer is approximately 1.01 tablespoons.

FuzzyChef
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    I'm sure that this volume/weight mismatch is well within the error in most cooking implement measurements. – bob1 Oct 05 '21 at 07:39
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    @bob1 especially trying to measure a bulk solid with a spoon. – Chris H Oct 05 '21 at 09:34
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    The error in the fluid ounce - weight ounce conversion (for water) and the difference in density between water and butter have opposite effects and are of similar magnitude, so they almost cancel. I'm not sure about the US, but in the EU this would all be within the allowable error for packaged foods. – Chris H Oct 05 '21 at 09:38
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    For this answer I went down the rabbit hole of "what substance IS the US fluid oz based on" and the answer seems to be "history". If there's any liquid where 1floz == 1ozwt, it's accidental. – FuzzyChef Oct 05 '21 at 17:28
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    "And who's going to complain about 1% extra butter?" Only a fool. It's like good times, and friends, hard to have too much of – TCooper Oct 05 '21 at 21:22
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    In what way is the liter "based on water"? The liter is based on length (i.e. "volume") not on mass or weight. (It was originally based on the volume of 1 kilogram of water under specified conditions, but that definition is now obsolete). – alephzero Oct 06 '21 at 02:55
  • It's still almost exactly 1kg of water. And it was originally based on water. – FuzzyChef Oct 06 '21 at 05:11
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    @FuzzyChef TIL that history is a liquid! – Janus Bahs Jacquet Oct 06 '21 at 10:10
  • No, the litre was NOT ever based on water. A litre has ALWAYS been defined as a 1000th of a cubic metre. A kilogram was originally defined as the mass of one litre of water under certain conditions. It's not defined that way any more. – Dawood ibn Kareem Oct 07 '21 at 18:57