## 2010-10-16

### Not loud, just spacious

"Yesterday" I looked at mass; in a few places within that article I mention volume, so I'd like to proceed in that direction "today".

The official SI unit of volume is the cubic meter (m3), but the common unit accepted for use along side SI is the liter (1 L = 1 dm3; reference prefixes for assistance). I'm going to choose to focus on the liter when it comes to the comparison to US customary units of volume.

US customary units are horribly overrun with measures of volume (even more so than the complications in measures of length): gallons, fluid ounces, cups, tablespoons, teaspoons, etc.! I'm going to only deal with gallons and fluid ounces; I'll let you handle the process of getting to those from the others. (Maybe it'll be extra incentive to simplify with down to consistent measures.)

Key conversion points for Volume (gallons / liters):
1 gal ≈ 3.8 L
2 gal ≈ 7.5 L
* 4 gal ≈ 15 L
8 gal ≈ 30 L
16 gal ≈ 60 L
With this I wanted to show the approximate relationship between 4 gallons and 15 L. Multiples of four can be easy to calculate and, as I've mentioned before, multiples of 5 are natural; which makes this match up almost clean.

For example, if you were trying to estimate how many Liters were in 20 gallons.... 20 gal = 4 gal * 5 ≈ 15 L * 4 = 60 L. Obviously, the approximation takes us off a bit, but you can see how this gets us in the same conceptual neighborhood.

Key conversion points for volume (ounces / milliliters):
* 1 fl oz ≈ 30 mL
8 fl oz ≈ 237 mL
16 fl oz ≈ 473 mL
20 fl oz ≈ 591 mL
Unfortunately, the approximation of 1 fl oz to 30 mL will quickly get out-of-hand as you multiply it out; therefore, I've included common fl oz measurements to help get the L equivalents into your memory. Keep in mind that 100 mL = 10% of a liter.