I have no idea how I got to thinking about cooking measures, but it's a topic that always confused me. How many teaspoons in a fluid ounce?

You only need to remember half-a-dozen rules

- Three teaspoons in a tablespoon.
- Two tablespoons in a fluid ounce.
- Sixteen ounces is a pound.
- A
**p**int (of water) is a**p**ound. - A cup is half a pint.
- Two pints is a quarter gallon is a quart.

Numbers 3-6 I have down. I always forget 1 and 2.

And for metric conversions you need to know two definitions:

- 1 inch is defined to be 2.54 centimeters.
- 1 US gallon is defined to be 231 cubic inches

US Customary system of measure.

tsp. Tbsp. fl. oz. cup pint quart gallon exactly 1 1/3 1/6 1/48 1/96 1/192 1/768 = 4.92892159375 mL 3 1 1/2 1/16 1/32 1/64 1/256 = 14.78676478125 mL 6 2 1 1/8 1/16 1/32 1/128 = 29.5735295625 mL 48 16 8 1 1/2 1/4 1/16 = 236.5882365 mL 96 32 16 2 1 1/2 1/8 = 473.176473 mL 192 64 32 4 2 1 1/4 = 946.352946 mL 768 256 128 16 8 4 1 = 3785.411784 mL

These are the definitions I grew up with. Since 1inch := 2.54cm (by definition), 1 cubic inch = 16.387064 mL. Since 1 US gallon := 231 inch^3 (by definition), 1 US gallon = 3785.411784 mL = 3.785411784 L, exactly.

The teaspoon is totally out of place here. Whose idea was it to introduce a THREE into this system? Why not use fluid drams, which are 1/8 fl.oz? Too late now, I guess.

Here are three different attempts to shoehorn the customary units of cup, tablespoon, and teaspoon into the metric system. None of them works well, since you end up with too many improper fractions like 50/3, 25/2, or 25/6.

Metric System (Canada, New Zealand -> 1Tbsp=15mL, 1cup=250mL)

mL tsp. Tbsp. cup Liter 1 1/5 1/15 1/250 1/1000 5 1 1/3 1/50 1/200 15 3 1 3/50 3/200 250 50 50/3 1 1/4 1000 200 200/3 4 1

Metric System (Austrailia -> 1Tbsp=20mL, 1cup=250mL)

mL tsp. Tbsp. cup Liter 1 1/5 1/20 1/250 1/1000 5 1 1/4 1/50 1/200 20 4 1 2/25 1/50 250 50 12.5 1 1/4 1000 200 50 4 1

Metric System (US FDA -> 1Tbsp=15m, 1cup=240mL)

mL tsp. Tbsp. cup Liter 1 1/5 1/15 1/240 1/1000 5 1 1/3 1/48 1/200 15 3 1 1/16 3/200 240 48 16 1 6/25 1000 200 200/3 25/6 1

Since SI simply doesn't define these units, why use them at all? Seems tto confusing in a global economy.