US Fluid Ounces to US Fluid Drams (fl oz to fl dr)
1 US fluid ounce equals 8 US fluid drams exactly.
How to convert US fluid ounces to US fluid drams
To convert US fluid ounces to US fluid drams, multiply the number of US fluid ounces by 8. This factor is exact. To go the other way, multiply US fluid drams by 0.125.
US fluid drams = US fluid ounces × 8
Example: 10 US fluid ounces = 80 US fluid drams.
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 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
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)
Related conversions
- US fluid drams to US fluid ounces (reverse)
- US fluid ounces to liters
- US fluid ounces to milliliters
- US fluid ounces to US gallons
- US fluid ounces to US cups
- US fluid ounces to cubic meters
- US fluid ounces to cubic centimeters
- US fluid ounces to US quarts
- US fluid ounces to US pints
- US fluid ounces to US tablespoons
- US fluid ounces to US teaspoons
- US fluid ounces to metric cups
- US fluid ounces to metric tablespoons
- Liters to US fluid drams
- Milliliters to US fluid drams
- US gallons to US fluid drams
- US cups to US fluid drams
See all volume units.