US Fluid Drams to US Fluid Ounces (fl dr to fl oz)
1 US fluid dram equals 0.125 US fluid ounces exactly.
How to convert US fluid drams to US fluid ounces
To convert US fluid drams to US fluid ounces, multiply the number of US fluid drams by 0.125. This factor is exact. To go the other way, multiply US fluid ounces by 8.
US fluid ounces = US fluid drams × 0.125
Example: 10 US fluid drams = 1.25 US fluid ounces.
Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.
About these units
US Fluid Dram (fl dr)
One eighth of a US fluid ounce (3.6967 mL). Used in old pharmacy measures.
Drachma, the Greek coin and weight, lies behind the dram. The Attic drachma weighed about 4.37 g and the Roman one about 3.41 g, and the apothecaries borrowed the name for both a weight and a liquid measure. The US fluid dram is one eighth of a US fluid ounce, 3.6966911953125 mL, and it divides into 60 minims. Its British imperial counterpart, spelled drachm in pharmacy usage from around 1900, is smaller at 3.5516 mL.
Doctors once used the dram as the size of a teaspoonful, and early nineteenth-century prescriptions assumed a teaspoon held 60 minims. By 1876 household teaspoons had grown to 80 to 85 minims, which made that shortcut unreliable for medicine. Pharmacy is now metric, but the fluid dram survives in the capacity of pill bottles and vials. In casual speech a dram of whisky is a small pour, about 25 mL in an English pub and 35 mL in Scotland, which is a different thing from the pharmacist's unit.
1 US fluid dram = 0.003696691195 liters (approximately).
Sources: Wikipedia: Fluid dram; Wikipedia: Minim (unit)
US Fluid Ounce (fl oz)
One 128th of a US gallon, 29.5735 mL. Not the same as the weight ounce, and about 4% larger than the imperial fluid ounce.
Fluid ounce began as an attempt to link volume to weight: the volume occupied by one ounce of some substance, such as wine in England or water in Scotland. Definitions varied by region and by liquid. When Britain defined its imperial gallon in 1824 as the space of ten pounds of water, the imperial fluid ounce came out so that an ounce of water weighs about one avoirdupois ounce. The US fluid ounce followed a different path and comes from the older wine gallon.
The US fluid ounce is exactly 1/128 of a US gallon, 29.5735295625 milliliters, about 4 percent bigger than the imperial one at 28.4130625 milliliters. American nutrition labels use yet another figure, treating one fluid ounce as 30 milliliters, a convenient rounding for serving sizes. The name is a trap, because a fluid ounce measures space while a weight ounce measures mass. A US fluid ounce of water weighs a bit more than an ounce of weight, while a fluid ounce of honey weighs considerably more.
1 US fluid ounce = 0.02957352956 liters (approximately).
Sources: Wikipedia: Fluid ounce; NIST SP 811, Appendix B.8: conversion factors for volume; 21 CFR 101.9: nutrition labeling household measures
Related conversions
- US fluid ounces to US fluid drams (reverse)
- US fluid drams to liters
- US fluid drams to milliliters
- US fluid drams to US gallons
- US fluid drams to US cups
- Liters to US fluid ounces
- Milliliters to US fluid ounces
- US gallons to US fluid ounces
- US cups to US fluid ounces
- Cubic meters to US fluid ounces
- Cubic centimeters to US fluid ounces
- US quarts to US fluid ounces
- US pints to US fluid ounces
- US tablespoons to US fluid ounces
- US teaspoons to US fluid ounces
- Metric cups to US fluid ounces
- Metric tablespoons to US fluid ounces
See all volume units.