Early on in my mulling over how to start this cooking blog, I decided to switch to the metric system.
Not just a little bit, when it was easy, but completely metric, and 100% SI (the International System of units, the official name for the metric system since 1960). And using methods that are now known to be superior to how nearly all other countries did their metric conversion. Now is the best time for the U.S. to have a metric- do-over, using only SI Units and best-practices.
When you look as closely at the so-called U.S. Customary System of units, you realize that it’s not a system at all, but instead consists of more than 17 different systems of units (I haven’t even counted the engineering and scientific units that aren’t metric), each of which has its own rules, none of which are coherent, each of which with a different origin, and each of which has been corrupted over the years such that they are particularly difficult to use.
So we’re going to stop using those evil systems, and use something simpler, that everyone can understand.
The metric system is “For all people, for all time.”—Nicolas de Condorcet
S: The U.S. measuring methods used in the kitchen are broken holdovers from medieval times.
O: The inertia of existing tools and techniques is very difficult to overcome.
A: The best way to fix problems of the ancient measures and techniques is to start fresh.
R: We will gradually develop better, easier, and safer techniques for cooking.The Metric Mulligan
I’m not really a golfer (though I still have my grandfather’s golf shoes and clubs), but now is a really good time for a metric do-over. The age of the geek cook is well underway, we hear a near-constant push for better STEM education, and there is a small cadre of metrication experts that has figured out why all of the previous efforts to switch to the metric system in the U.S. have failed.
We’ve been trying to switch since 1866, but even though the U.S. Constitution gives the federal government the right to unilaterally define the units of measurement, not one President or Congress since has ever used the authority given to them to fix the above mess of units.
Perhaps that’s for the better, because if we had made such a bold move even as recently as 1992 (the last official date the U.S. was supposed to have finished metrication), we would likely have done it in the same fashion as other countries that are still encumbered with their previous measurement systems. The U.K., Canada, and Australia still use the Imperial system in large swaths of their everyday lives. In France, the locals still order beer in pintes, because it’s more than the metric serving of beer.
Aside from the surprising discovery that using centimeters (and centiliters, deciliters, etc.) dooms the conversion to take many decades (as outlined below), there are many little things that haven’t been done in most other countries, foremost among them basing standard sizes on preferred modules—such as 100 milliliters for liquids, 100 grams for other foods, and multiples of 100 millimeters for lengths.
By using such rational multiples, we will make it easier to calculate cost per unit, food energy per unit, and make it much easier to double or halve recipes.
It’s been 131 years since the U.S. first legalized the metric system in trade, and it will take longer than that again if we keep trying to convert using the old ways. By then, the U.S. will no longer be a superpower or any sort of technological leader, and our standard of living will have greatly diminished.
Instead of 131 years, we could do it in less than 5 years, as Sweden demonstrated is possible. Let’s start today.
The Metric Maven
More than any other resource, the one thing that convinced me metric was easier was the Metric Maven, a blog kept by Randy Bancroft, P.E., an electrical engineer in the Denver area. Randy has been posting one or more articles a month (on the 10th of each month, also usually on the 20th and 30th, plus on π day) like clockwork since 2012, and his insight into the proper ways in which to use metric is unparalleled. Likewise, the Maven will tell you he acquired much of his insight from the late Pat Naughtin of Australia, who founded the site Metrication Matters, and was one of Australia’s key experts in metrication (the process of converting from traditional to metric units).
I long ago realized the metric system was superior in capabilities, and potentially easier to use, than the mish-mash of misdeal units known as the U.S. Customary System (USCS), but that the sheer inertia of inches and ounces made it impossible to switch unless you went whole-hog metric, and dragged others through the mud and over the fence to the pasture with you.
Our so-called “U.S. Customary System” (USCS) should really be called the U.S. Medieval Units, because most of our units were originally defined back during the Medieval period, with some dating to at least Roman times. Our “system” doesn’t even have an official name defined by Congress. It is in fact a mish-mash of the following 17 systems (all but the last 3 are directly relevant to cooking!), plus several other specialized ones, so perhaps we should call them Yankee Doodle Units?
One of the most visible problems is that of the ounce. There are at least three U.S. units that are called ounces—two are weights and one is volume. Using the same word for different meanings is called a false friend, and there are a whole bunch in cooking measurements, as you can see below, including dram, ounce, pound, tablespoon, pint, quart, pottle, and gallon.
- Our binary subdivision system of halving each measure leads to unwieldy fractions such as 1⁄2, 1⁄4, 1⁄8, 1⁄16, 1⁄32, and 1⁄64, and this division dates to at least the Fifth Dynasty of Egypt—4.300 years ago!
- One grain of barleycorn from the middle of the ear, is one grain—the base unit of all of the systems of weight detailed below, except that of the carat. (But if you’re talking about the Tower pound, of old London, that’s a different species of grain.)
- The inch was originally defined as the length of “three barley-corns round and dry”, and remained based roughly on that measurement until 1959, when it was redefined in reference to the metric system meter. The barleycorn definition is found in the written record as early as 1303, but it probably existed much earlier, likely as early as King Edgar’s reign. But there are two inches in the U.S.—one for measuring land (the U.S. Survey Inch), and one for measuring everything else (the International Inch).
- If you really want to keep using the foot and inch, you should also use the other measurements related to it, including (in ascending order of length):
- The digit (the width of the tip of the middle finger)
- The finger (the width of the lower knuckle of the middle finger)
- The palm (the width of the hand without the thumb)
- The hand (the width of the hand with the thumb held closed, defined by NIST as 4 inches; the height of horses is still measured in hands, of course)
- The shaftment (the width of the hand with the thumb extended)
- The Avoirdupois weight system (which consists of the base unit grain, 27 11/32 grains=1 avdp. dram,16 avdp. drams=1 avdp. ounce, 16 avdp. ounces=1 avdp. pound, 25 avdp. pounds=1 avdp. short quarter, 28 avdp. pounds=1 advp. long quarter, 4 avdp. short quarters=1 avdp. short hundredweight (100 lbs), 4 advp. long quarter=1 avdp. long hundredweight (112 lbs); 20 short hundredweight avdp=1 short ton avdp, 20 avdp. long hundredweight=1 avdp. long ton) uses the old English pound, which was defined as the weight of 7000 barleycorns, and remained the definition of the pound until 1959, when it was redefined as the International Pound, and based on the metric system. The pound goes back at least to Saxon times (500 to 1066 AD). But even though both the U.S. and the U.K. use the International Pound, for all weights units larger than a pound, the two systems are different.
- Troy weight (which consists of the base unit barleygrain, 24 grains=1 pennyweight, 20 pennyweights=1 troy ounce, 12 troy ounces=1 troy pound) used for weighing gold, silver, and other fine metals. This system dates to at least 1390, perhaps 1147, most likely to the 9th century AD, but really dates to at least the Roman monetary system, because the abbreviation for pennyweight is dwt, short for denarius weight. Why would you care about Troy weight as a cook? For buying edible gold leaf, for these Champagne truffles, of course.
- Apothecaries weight (with a base unit of the grain (G.j. or ), pinch (), little handful (P.j.), half-handfull (M. ß), handful (M.j. or ), where 20 grains=1 scruple (℈ or ), apoth. half-dram (), 3 scruples=1 apoth. dram (ʒ or ), apoth. half-ounce (), 8 drams=1 apoth. ounce (℥ or ) , and 12 apoth. ounces=1 apoth. pound (℔ or ), so much as necessary (q.s., short for quantum sufficiat)), which was until recently used by pharmacists for measuring medication, and where drams are nearly twice the weight of an avoirdupois dram, and a pound has only 12 ounces, not 16 as in avoirdupois. These are the same as the pre-1864 British Apothecaries’ weights, but different from the British Apothecaries’ weights in effect 1864–1971.
- Apothecaries volume (with a base unit of the minim (♏︎), where 1 minim=1.23223 drops (gtt), 60 minims=1 fluid dram (fʒ), 8 fluid drams=1 fluid ounce (f℥), 4 fluid ounces=1 gill, 4 gills=1 pint (), 2 pints=1 quart ( ), 4 quarts=1 gallon (C.)) used to be used by pharmacists (the modern descendants of the apothecaries), and even though the U.S. medical establishments have pushed the medical industry to switch entirely to the metric system, the US FDA still occasionally mentions fluid-drams, and they are even mentioned in federal regulations, including 21CFR201.51, 2017 edition. The British Apothecaries’ system of volume measurements is different, both in the number of ounces to the pint (20, but of course), and in that it uses fluid scruples in-between minims and drams.
- U.S. liquid gallon and its divisions (U.S. fluid ounce=1⁄4 U.S. gill (or 2 U.S. tablespoons), 1 U.S. gill=28.875 cubic inches, 2 U.S. gills=1 U.S. cup, 2 U.S. cups=1 U.S. liquid pint, 2 U.S. liquid pints=1 U.S. liquid quart, 2 U.S. liquid quarts=1 U.S. pottle, and 2 U.S. liquid pottles=1 U.S. liquid gallon) are derived from the English gallon created by King Edgar, who reigned from 958 to 975 AD, and most recently based on the Winchester wine gallon of 1495 by King Henry VII of England.
- U.S. dry measures (dry pint, dry quart, dry gallon, peck, bushel) are used for measuring grains, berries, and a few other food types. These are based on the Winchester bushel of 1496, but may date to a bushel from 1266 created by King Henry VII of England.
- American cooking measures (saltspoon, coffeespoon, fluid dram, teaspoon, dessertspoon, tablespoon, fluid ounce, wineglass, gill, cup—each is twice the volume of the previous), which once were specific fractional divisions of a fluid ounce as described above, but have long since been confused and forgotten, such that there are 3 teaspoons in a tablespoon everywhere on the planet except Australia, which remembers that the correct number is 4.
- Approximate measures (drop, smidgen, pinch, splash, dash, handful, mouthful, finger, wineglass, teacup, coffeecup, jug, pitcher, etc.), where the definition has gotten so muddled over the years that they have no real meaning, even though all originally had known definitions, such as using three fingers for a pinch (used mostly for flowers, in apothecaries’ measures). Even a drop is approximate because its size varies with the surface tension of the liquid and the diameter of the opening in the dropper.
- Food Calorie—Did you know that calorie and Calorie are two different units, and one is a thousand times bigger than the other?
- British Thermal Units—This is how heat energy is measured, but there are a number of different BTUs, depending on what you’re measuring.
- Scoop sizes—More correctly known as dishers, these have numbered size designations based on how many level scoops per quart that size holds. So you can multiply the scoop size by 9.464 mL to figure out the capacity.
- Fahrenheit—the temperature scale first defined in 1724, and redefined several times since. The metric Celsius scale is used by nearly 95% of the Earth’s population, and has easier to remember values for melting ice (0 °C), and boiling water (100 °C).
- Manufacturers’ Standard Gauge for Sheet Steel—used to measure the thickness of pans and baking sheets. Not the same as screw gauge.
- Carat weight—used for measuring gemstones, and originally based on the carob seed.
- Mariner’s measures (foot, 8 feet=1 fathom, 120 fathoms=1 cable, 7.5 cables=1 nautical mile, 6085 feet=1 nautical mile, one minute of latitude=1 nautical mile)—used by sea-going vessels and airplanes.
- Gunter’s Chain Units (1 link=66⁄100 of a survey foot, survey foot, 3 survey feet=1 survey yard, 1 rod=5 1⁄2 survey yards, 4 rods=1 survey chain (66 survey feet),10 chains=1 furlong (1⁄8 survey mile, or 660 survey feet)—is what land surveyors and the county taxman use to measure the land your house or apartment is built on. They use units that you’ve likely never heard of, such as links, chains, rods (also perch or pole), and furlongs, but also feet and miles, though these feet and miles are not the same as the ones you see on road signs and rulers, because when the U.S. foot, yard, and mile was redefined in 1959 to be based on the meter, it was too difficult to redefine all of the land surveys, so the surveyor’s inch and mile, also known as the statute mile, retain their original, pre-metric definition, and can’t be interchanged with the modern mile without conversion.
Using this hodge-podge of medieval systems is pure insanity! I can’t and won’t do it anymore, and neither should you. Metric is so much simpler, as you will gradually discover through the methods CFOG teaches.
Among the many great essays of the Maven, Euphemism and The Metric System stands out as the best way to understand just what a confusing, ill-defined mish-mash of ancient and medieval units the U.S. uses. To that, I can add these cooking-specific problems with the U.S. traditional units:
- A pint of milk or beer is 16 ounces, but a pint of strawberries is 12 ounces if grown in Tennessee and just 8 ounces if grown in Iowa (according to the U.S. government). I’ve seen people ask on Quora how to measure a pint of strawberries, and the answer that has the most votes is the one that is most wrong (start with one cup of water and add strawberries until you get three cups of water and strawberries). The real answer is much simpler—just use one basket of strawberries you buy at the grocery store, because they’re all dry pints, which are defined as 33.6 cubic inches.
- It’s hard to remember that the U.S. base unit of length is divided into 12 parts, but the base units of weight and volume are divided into 16 parts, because someone goofed way back when and forgot that an ounce comes from the Latin word “uncia”, meaning 1/12.
- A U.S. cup is officially 236.59 mL, but the FDA says it is 240 mL—enough to make a difference for some ingredients in baking.
- Many recipes from England can not be used in the U.S. without careful unit translation, because in England, fluid ounces are 28.4 mL with 20 of these per pint, while in the U.S. they are 29.6, with 16 of these per pint. So U.S. fluid ounces are bigger, but English pints are bigger. So a recipe written in England that uses pints and quarts means a volume that is 20% greater than you can measure with a U.S. measuring cup.
- Many people have trouble remembering the difference between teaspoons and tablespoons, especially between their official abbreviations—tsp and tbsp. A teaspoon is defined in the U.S. and the U.K. (and most of the rest of the world) as 5 mL, with the tablespoon being 15 mL, but in Australia, the tablespoon is officially defined as 20 mL—33% more than in the U.S.—a full extra teaspoon. So what happens when you don’t realize that a recipe you think is American is really Australian, and it’s giving you measurements in ounces and tablespoons? The ounces will be close, but the tablespoons will be 1/3 greater.
- Let’s talk about pints some more. I’ve tallied more than 8 different pints of beer currently in use around the world, all differing by a noticeable amount. How big of a problem is this? If you ask for a “pintje” of beer in Flanders, Belgium, you’ll get 250 mL (a little bit more than 1 U.S. cup), while if you ask for “une pinte de bière” in Quebec, the server is legally required to serve you 1 Imperial Pint, which is 1136 mL, more than double the U.S. fluid pint of 473 mL.
People are generally resistant to change—until they are hurting enough. The hurt is there right now, even if you don’t realize it. Our lack of fluency with the messed-up measuring system the U.S. uses means most of the population does not have the tools or information needed to quickly understand food energy content, its relation to food portion sizes, consistent price-per-unit comparisons, and many other important issues.
- U.S. cooks prefer using measuring cups to scales, and a great many kitchens don’t even have a scale, much less one that measures in grams. But the amount of flour you put in a 1-cup measuring cup varies greatly, Depending on how you fill that cup, it can weigh anywhere from 4 ounces to 5 ounces—a 50% variation that will make a significant difference in baking. See what Kenji and Cook’s Illustrated have to say on the topic, if you don’t yet believe me.
- Most models of electronic kitchen scales can be set to grams, but some models revert to pounds and ounces every time they power up.
- Even among scales that read in grams, most only count whole grams (one standard M&M has a mass of one gram), which is far too coarse for measuring small amounts of spices, and even a single cup of coffee.
- It is virtually impossible to find metric measuring spoons or cups in the U.S. Read the Maven’s The Invisible Metric Embargo for a more detailed look at this.
Call-To-Action: Ditch the inch and buy yourself a millimeter-only ruler that is 300 mm long. This is about the size of a 12-inch ruler, and 3 mm longer than the height of a sheet of A4 metric paper, so you’ll be able to measure any typical document with it, while it’s still short enough to live on your desk or in your toolbox. Whatever you do, never buy another measure with centimeters on it! Please read The Design of Everyday Rulers to understand why this is such an important rule.
So I’m going to eliminate all of those problems from the modern kitchen methods that I teach here, and just use the modern metric system, officially known as SI.
The single most important reason you should learn from the Metric Maven’s writings is his promotion of “Naughtin’s Laws“, which are 4 simple rules that make using the metric system so much easier than either customary units or how other countries use metric:
- Dual-Scale Instruments are Evil
- Tools with both inches and millimeters, or ounces and milliliters, make it possible to continue using the U.S. Medieval units forever, they cause confusion, and generally have the U.S. Medieval units presented preferentially to the user (fluid ounces facing the right-handed holder of a measuring cup, and inches on the top of a tape measure held in the right hand). Read the Maven’s The “Preferred” Measurement System of the US article for a comprehensive look at the issue.
- Prefer Measures Without Decimals
- Decimals complicate measurements, calculations, and break the nice segmentation of switching unit prefixes only every thousand units.
- Don’t Change Measures in Midstream
- Mixing measurements units, even if using only metric prefixes, makes comparing different items far more difficult. If you use only milliliters for drink bottle sizes, for instance, it becomes far easier to tell the difference between an airline bottle of liquor (50 mL), a can of beer (355 mL), a gross of beer in Germany (500 mL), a standard bottle of wine (750 mL), or a magnum of wine (1500 mL). No liters, no deciliters, no decimal point. Just one unit that’s easy to visualize—a cube 10 millimeters on a side, full of liquid.
- No Centimeters!
- This rule follows quite naturally from rules 2 & 3 above, but is so important, and so little known, that it needs to be stated in a rule of its own. The general form of this rule is to avoid completely metric prefixes that aren’t multiples of 1000. No deci-, deca-, or hecto- prefixes, ever. Start with millimeters, and stick with them throughout a project. If the lengths can all be expressed in whole meters, then start with meters, and never use millimeters or kilometers. Think this is just a silly rule from a silly Aussie? No, it’s the recommendation of major U.S. building standards organizations, as the Maven points out in Building a Metric Shed.
There are a few other rules that should be formalized, such as that It is “preferable now to use different prefixes for every three orders of magnitude” (Isaac Asimov’s words), the 100 mL module size for liquids, 100 g size for other goods (so you could divide a 600 g package of ground beef evenly), and the 100 mm module size for construction, but those four are the most important, and the ones you should start with.
The single biggest ah-ha moment I had was when the Maven taught me how evil centimeters were. I had long believed them to be an essential and fundamental part of the metric system, what with their common existence on rulers, measuring tapes, and the height of Commonwealth subjects.
But a centimeter is too large to use for almost anything without tacking on a decimal point, and that decimal point instantly introduces fractions, which are one of the biggest problems with the inch. Shift that decimal point one digit to the right, and you wind up with millimeters, which are accurate enough for just about anything except machining, thus making adding and subtracting measures far easier than with duodecimal or decimal fractions.
Using the millimeter also makes it easier and faster to ditch the inch. In Australia, the building industry chose to ban the centimeter, and completed the switch to metric in less than two years, way back in 1974–1976. For the Australian textile industry, which decided to use the centimeter, the “transition is still muddled, bitter, and enormously expensive (nowhere near completion after more than 40 years — and counting)“, according to the experience of Mr. Naughtin.
The ways in which I expect going metric in the kitchen will benefit you include:
- Your ability to replicate recipes, especially with baked goods, will significantly improve.
- Measuring many ingredients by mass instead of volume will let you use fewer mixing bowls, so you’ll have fewer things to clean.
- You will be able to exchange recipes and cooking techniques with friends and relatives that live in or were born in other countries.
- You will feel more like you’re living in the 21st century.
To see what direction CFOG is headed in with measuring units, I invite you to start reading the Metric Maven. If you’re a true geek, the best way is to do what I did, and read all of his essays in chronological order. Start with his first essay, “The Invisible Infrastructure“, and then click the “Next →” at the top of each article to read the next-newest one. (Note, the previous/next navigation may not work on all mobile browsers).
When you catch up to his latest post, you will know nearly everything I have learned about the metric system.