By The Metric Maven

On March 2nd, 1962 Wilt Chamberlain set the single game scoring record in the NBA. He scored 100 points. This record is an astonishing achievement. The game was not televised, there is no video of it, and only an audio recording of the final quarter exists. The photograph taken by a sports photographer is iconic and succinct. Wilt holds up a piece of paper upon which the photographer has written 100. The closest anyone has come to this record since, was when Kobe Bryant scored 81 on January 22, 2006. Some professions become obsessed by 100. This number is considered a milestone (yes The Metric Maven can use this as a metaphor) for some television programs. The program is then eligible for syndication. Frylock from *Aqua Teen Hunger Force* becomes obsessed by 100, in their one hundredth episode. This is the 100th essay published at The Metric Maven, and so 100 is the topic.

Why do I bring this up? Well I’ve become concerned that people might have the impression I don’t like 100 because I would vanquish centimeters (actually centi-anything). There are many cases where I encourage, in fact almost demand the use of 100. Much like the epiphany about eliminating centimeters, it took me a while to embrace 100, and understand its importance in other metric contexts. Let me begin at the beginning, which involves gas mileage.

I had stumbled across the fact that most Europeans do not compute their fuel efficiency in Liters/kilometer, but in Liters/100 kilometers. I could not see why on earth they would do this. What possible benefit could it have? On my last trip, my car got 32.87 miles to a US gallon, which is 7.16 Liters/100 kilometers. The formula is Liters/100 Km = 235.21/mpg. Here is a quick table:

MPG L/100 Km

10 23.52

15 15.68

20 11.76

25 9.41

30 7.84

35 6.72

40 5.88

45 5.22

50 4.70

The liters per 100 Km values give a much better intuitive understanding of the actual fuel efficiency. Fearlessly using Naughtin’s Laws, let’s remake the table in terms of milliliters

MPG mL/100 Km Gasoline Volume Saved

10 23 520

15 15 680 7840 mL (10-15)

20 11 760 3920 mL (15-20)

25 9410 2350 mL (20-25)

30 7840 1570 mL (25-30)

35 6720 1120 mL (30-35)

40 5880 840 mL (35-40)

45 5220 660 mL (40-45)

50 4700 520 mL (45-50)

100 2352 2348 mL 50-100 MPG is close to difference from 20-25 MPG

What this shows us is that going from 45 MPG to 50 MPG saves 520 mL. Bottled water is generally sold in 500 mL bottles. What’s the difference when we go from 20 to 25 MPG?—2350 mL which is over two liters (i.e. a two liter bottle of soda). We can immediately envision the change in fuel economy, and it is large. Going from 10 to 15 MPG saves 7840 mL or almost *four* 2 liter bottles of soda. Going from 45 to 50 MPG saves only about two aluminum cans of soda. We can see that increasing fuel efficiency from 20-25 MPG (5 MPG increase) saves about the same volume of fuel as going from 50 MPG to 100 MPG (50 MPG increase).

My friend Rick owned a 1968 Plymouth Roadrunner in the 1970s. It was the era of Muscle Cars and Ed “Big Daddy” Roth. Rick’s car had nearly a 3/4 cam and was designed for high performance, *but not fuel efficiency.* It was the last of the cars from the era defined by the film American Graffitti, which was released in 1973, and proved to be a swan song. Rick’s Roadrunner averaged about 10 miles per gallon or 23.5 L/100 Km. My current car averages about 35 MPG or 6.7 L/100 Km. It takes 16.8 liters less than Rick’s old Roadrunner to traverse 100 Km. Rick’s old car may seem like an anachronistic gas guzzler, but should you happen to drive an M-1 Abrams tank, it has a fuel efficiency of 470 L/100 Km. Now that’s a gas guzzler.

My friend Kat on the other hand, is at the other end of the fuel efficiency spectrum She drives a 2010 Honda SH150i and has a calculated mileage of 114 MPG. Wow, that’s 2.1 liters per 100 kilometers. While that’s serious fuel efficiency, Kat tells me the 2011 Genuine Scooter Company’s Stella scooter claims 140 MPG or 1.7 L/100 Km!

This is all very interesting, but it didn’t still didn’t make me a 100% 100 convert.

What caused the realization of how useful 100 could be was when I worked on controlling and quantifying my Calorie intake. (I will set aside why I’m not using kilojoules for the moment, with a promise to write about it in the future.) I had begun doing all my cooking with grams and mL. Years ago I had used a now out of print book called *The All in One Calorie Counter*. It had everything in it. When I looked on line I found an incredible website to help me, which is now gone.

The website allowed one to search for almost any type of food, and the output was in calories/gram and grams/100 calories. Like the fuel efficiency numbers, I could quickly understand how “calorie dense” different foods are at a glance with grams/100 calories. Because I had begun using a scale when I went to metric cooking, I could easily measure the mass of any food in grams. This in turn would allow me to compute the total calories very quickly. Here is a list of some common foods and their grams/ 100 calories.

One can immediately see that bacon is very calorie dense with 19 grams per 100 Calories. The grams/100 Calories for meats increase up to 125 g/100 Calories for chicken. This table immediately shows one why so much chicken is consumed by people trying to reduce their calorie intake, and hamburger is not. It shows that if you’re given the choice between butter and sour cream on a potato, sour cream has far fewer calories for the same mass. Flour and sugar have equivalent energy densities.

When I would weigh out food, I could quickly halve or double the grams to obtain 50 calories or 200 calories of a food. I was very surprised at the convenience. Measuring the components out of which I make a sandwich, has given me a feeling for the amount of calories in different foods. I never had that intuition when using non-metric methods. The most important aspect for me is that because of US Government food labeling requirements, I can compute the grams/100 calories for any food I purchase. I just use this simple formula:

For instance suppose we use this label from eggs as an example. The egg has a mass of 50 grams (1 serving) and contains 70 Calories of energy. We compute 100*50/70 which gives us 71.4 grams/100 Calories. I would round this to 71 grams/100 Calories. We see immediately from our table that it’s similar to eating Ribeye Steak at 65 grams/100 Calories. It is about two times fewer calories than eating hamburger with the same mass.

This is when I was completely convinced of the utility of 100 in certain instances. You can imagine how hot under the collar I became when I found out that some groups want to take grams off of the nutritional labels on foods and change them to Ye Olde English! This would screw me up seriously, and once again be a complete retreat from improving our quality of life in the US by adopting the metric system.

The use of 100 has provided options in my Engineering work that I did not previously have. When a radio wave (electromagnetic wave) travels in a coaxial cable transmission line, like the one attached to a television, it slowly loses energy. One can measure how much energy enters this length of cable, and how much is remains at its end, divide the two values, and create a logarithmic loss “unit” called the decibel. When I measure the losses of electromagnetic waves through materials and transmission lines, it has been traditionally described in decibels/inch. Decibels per meter does not work well for high loss materials and and decibels per inch does not work well for low loss materials. It suddenly struck me one day that perhaps decibels per 100 mm was a good candidate. It was, it works, and I now use it exclusively.

In the 1970s, Australia, early in their metric switchover, pressed for a uniform price per kilogram for foods. Kevin Wilks in his book *Metrication in Australia* states:

In hindsight, the decision to press for “per kilogram” only pricing was unfortunate. While pricing on a common unit basis facilitated price comparisons, it gave no guidance to the public on sub kilogram quantity selection…….

***

In Canada and Singapore, fractional pricing based on halves and quarters of the kilogram was forbidden, but prices per kg or per 100 g were permitted. This simple device ensured that in those countries sub unit quantities were obtained as multiples of one tenth ofÂ a kilogram and successive halving was avoided……

For Australia to gain the fullest benefit of conversion to a decimal system of weights and measures, it was inevitable that authorities permitted and encouraged “per 100 g” pricing in addition to “per kg” pricing

I’m not as obsessed with 100 as Frylock, but I’ve realized it can give me a completely different way to look at important quantities. In the proper situation, 100 is the best way to go.

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Maven, I was waiting for you to discover the reason for per-100. Think a moment. Per one hundred. Per centum. Some banks talk of an interest rate “per centum per annum.” It’s a percentage!

As we speak, U.S. medicine is planning on adopting SI more fully in its clinical reports. One unit of concentration currently used is the amount measures per deciliter, or per 100 mL. For example, blood glucose is measured in milligrams per deciliter (mg/dL). When I was still in school just after Hannibal’s big mountain climb, the expression used was actually pronounced out loud as mg% or milligrams percent, which is why I think we concocted this mg/dL while the rest of the world expresses the concentration more chemically, using the amount of substance per liter, or mmol/L. Liters per 100 kilometers follows that concept, so it’s like “liters percent of distance.”

Fun post. I didn’t know the Metric Maven was a closet-former-100-disliker.

Regarding food labels, in Germany (and elsewhere, probably everywhere) the measured quantity is not a “serving” but 100 grams. So it’s easier to compare two products on that objective measure rather than a “serving,” because everybody would agree that there aren’t really 4.x servings in a container of Ben & Jerry’s.

The rest of the world provides nutrition labels that state the quantity per 100 grams, which is a much much easier way to work, than your reverse g/100kcal.

Regarding nutritional labels, and where the quantity per 100 g or 100 mL is used, and where serving quantity is used.

For whole products, the 100 g or 100 mL is used. Examples.. block of cheese, can of beans, can of soup etc

For products that are not whole, the serving size is used. Example sliced bread. The serving size is one slice. It may also state the weight of the slice, but it’s not practical to apply the quantity per 100 g to sliced bread, and therefore the serving size (one slice) is used.

Fuel efficiency.. is MPG, or km/L. The variable measure is the distance. The fixed measure is the volume. It is measuring the efficiency of fixed measure (the gallon or litre) in distance travelled measured in miles or kilometres.

Fuel consumption.. is L/100km, or G/100mi. The variable measure is the volume. The fixed measure is the distance. It’s measuring the consumption, or use of, the variable measure (the litre or gallon) over a fixed distance (100 km, or 100 mi)

It’s easier to calculate the amount of fuel consumption, and therefore the cost of fuel, for a set travelling distance, using the fuel consumption model.

For example.. If my car uses 8.6 L/100km, I know that on a 450 km journey my car would use 8.6 x 4.5 = 38.7 L although to be safe I’ll put 40 L in the tank, because 8.6 L is an average amount.

Well, L/100 km is a typical example of “customary metric use” (still the norm almost everywhere); while a more correct SI version, in this case, would of course be m^3/Mm (cubic meters per megameter): perhaps not equally intuitive in today’s context (sadly, almost nobody uses the megameter in daily life), but certainly more elegant.

(BTW, 100 km = 10^5 m, but no SI prefix exists for 10^5.)

Well, L/1000 km, or L/Mm, would multiply existing numbers by 10 and largely eliminate the need for a decimal point. I suspect 1000 km is a rough approximation to many people’s monthly drive, or at least their annual drive could be rounded to the nearest thousand and annual fuel savings of different vehicles readily compared.

I have made this argument before, but I doubt my “dead horse” will get up and run.

I think the reason L/100 km caught on as opposed to L/Mm is that in the days when fuel consumption numbers were first being used people might travel 1000 km not in a month, but maybe a year. Also, I believe the myriametre was in common use at that time.

http://www.wikipedia.or.ke/images/thumb/e/e4/Alter_Grenzstein_Pontebba_01.jpg/398px-Alter_Grenzstein_Pontebba_01.jpg

It wasn’t until the wide use of the “Autobahn” system of highways came into general use that people would travel greater distances in the shorter time. By that time the per 100 km was too ingrained to change. But, at least mentally you can read 8.2 L/100 km as 82 L/Mm.

MetricMaven,

Why are you opposed to using symbols?

“On my last trip, my car got 32.87 miles to a US gallon, which is 7.16 Liters/100 kilometers. The formula is Liters/100 Km = 235.21/mpg.”

Why spell out litres per 100 kilometres and not just shorten it with legal symbols to L/100 km? You used “MPG” and not miles per gallon. Why use an abbreviation for FFU (FFU shorthands are not symbols) and not symbols for SI?

Congrats!!!!