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Comment by bbrazil | Hacker News Reader

I usually use Google (or for things like oz, switch the units on my kitchen scales).

You probably know this, but given the context (GP was talking about measuring cups) it's important to know that ounces can refer to a unit of volume (1/128th of a gallon) or a unit of weight (1/16th of a pound). They are equivalent for water, almost equivalent for most liquids, and not equivalent for most solids. It's just like if we had one word that meant both liters and kilograms.

>ounces can refer to a unit of volume (1/128th of a gallon) or a unit of weight (1/16th of a pound)

Unbelievable. Surely at some point someone must have realised thats a terrible idea?

That's why you'll hear the phrase "fluid ounces".

Well, that's a bad way to look at it.

A fluid Oz is 1/16 of a pint.

An oz of weight is 1/16 of a pound.

A pint of water weights 1 pound ("A Pint's a Pound, the World Around").

Aside: I actually like the customary system for fluid measurements; it's based on halves and as such is divisible by eye, not requiring graduations.

> or a unit of weight (1/16th of a pound).

Or 1/12 of a pound, though, to be fair, I don't think anyone uses troy ounces in recipes.

> They are equivalent for water, almost equivalent for most liquids, and not equivalent for most solids.

Even solid foods are often right around the same density of water, so its often quite close for solid foods. (And, usually, if volume is intended rather than weight, listings will specify fluid ounces.)

I use the windows calculator's "convert" functionality. :/

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