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The metric system, exposed

Ok, so I wanted to make a really didactic post explaining all about the metric system, since I’m aware that a large portion of the food blogging community comes from the United States where it isn’t generally used, and so they might not be familiar with it, which is a shame because it is actually such a convenient and user friendly tool, a piece of cake to learn and, if you are capable of dealing with the incredibly intricate imperial system (which is no walk in the park!), the metric one will seem so easy in comparison.

Measuring tape

The thing is, as I started to write down and explain all the important concepts, lots of other things came up that needed explaining too, since I wanted it to be as unassuming about mathematical knowledge and easily approachable as possible, and I kind of found myself writing something that was turning into a textbook because I didn’t want to leave any loose ends and wanted it to be very comprehensive and methodical and thorough. But no one comes to a mostly food blog to read The Big Book of the Metric System, so when I got to the point where I was getting into explaining the concept of multiplication I gave up and decided to just kind of wing it and write a rather casual post about it instead, sticking to the parts that are more relevant to cooking and hoping that, if you’ve never used it before, you’ll get some basic understanding of the whole concept. So here we go:

First off, let us begin with the meter (which symbol is the letter m). The meter is the main unit of length and, as our 3rd and 4th grade teacher made us learn by heart (threatened by the fact that she’d knock the top of our heads with the humongous rhinestone from one of her various rings if you failed to say it right, cause she was old school like that), is the ten-millionth of a quarter of an Earth meridian, or the length between two marks on a certain platinum and iridium bar kept in the museum of weights and measurements in Paris or, as the far less romantic current definition goes, the distance that light travels in a 1/299792458 of a second in vacuum, but you’re probably much better off knowing that it’s just a little bit bigger than a yard, so it’s quite easy to fathom coming from the imperial system.

When we want to measure little things in our everyday life, we use centimeters (cm) and milimeters (mm). You might be familiar with those prefixes and may have guessed that there are 100 centimeters in one meter (just like there are 100 cents in one dollar) and 1000 milimeters in one meter, so there are 10 mm in each cm. A milimeter is about the width of a thread of yarn, or the thickness of a small coin, whereas a centimeter is about the width of one of my fingers because I have pretty small hands. Keep in mind that an inch is about 2.5 cm, so picturing a cm shouldn’t be too hard.

measuring tape

I am 160 cm or 1.60 m tall, which equals 5 ft 3” and a 9 inch cake pan is about 23 cm for some reference.drawing tools

When you want to measure longer distances, you normally turn to kilometers (km), being 1 km equal to 1000 meters, and so 1 mile = 1.61 km. The speed limit in Spanish highways is 120 km/h, which would translate to 74.6 mph.

highway sign with kilometric distances

But the great thing about the metric system is that everything is easily related. Let’s see. If you take 10 cm (roughly 4 inches) (which is called a decimeter (dm) because 10 dm make 1 m), and you make a cube which side measures that, then the volume that fits into that cube equals 1 liter (l) (which is about a tiny sip less than a quart), but wait! It gets better, because the amount of water it takes to fill that cube weights exactly 1 kilogram (kg) (which equals 2.2 lb, or 35.27 oz).

I weight around 55 kg (121 lb), and things like flour, rice, sugar and dry beans come in manageable 1 kg packages, whereas I like to buy my chocolate chips in bulk, and they come in 2.5 kg (5.5 lb) wonderfully big bags.

chocolate chip bag

Also, if you take that water we were talking about, the temperature at which it freezes is 0 ºC (degrees Celsius or centigrades) (which would be 32 ºF), and the temperature at which it boils is 100 ºC (or 212 ºF). Easy, right? Today it is around 15ºC here (59 ºF), and you’ve got a fever if your tempreature is over 37 ºC (98.6 ºF) so you get the idea.


And, for some diversity, just like with meters, centimeters, etc, other widely used units are the mililiter (ml) and centiliter (cl) for volume, and the gram (g) for weight (and yes, I know it’s mass and not weight, but I think we all understand what I’m talking about). We don’t normally use anything smaller than a gram since, being 1000 g equal to 1 kg, you’re not likely to weight anything lighter (28.35 g make 1 oz, and 454 g make 1 lb), but you might want to know that 1000 miligrams (mg) make up 1 gram.

Soda, for instance, comes in 330ml (11.15 fl oz) cans (instead of 12 fl oz, or 355 ml, like in the US) and wine in 75 cl (25.4 fl oz) bottles.

So, recapitulating, here’s what you’ll be using more:

1000 mm = 100 cm = 1 m = 0.001 km
1000 ml = 100 cl = 1 l = 1 dm³
1000 g = 1 kg

And, since American recipes heavily rely on volume measurements that are specific to cooking and baking, I made a little table (click on it to enlarge it and make it actually readable) with volume equivalents for gallons, quarts, pints, cups, ounces, tablespoons, teaspoons and mililiters that I hope will come in handy. To read the table: the number that’s on the same column as one of the units on the top row tells you how many of those units are in the one that’s on the first column of the same row the number is. This sounds incredibly complicated, so here’s an example: If you want to know how many tablespoons are in one pint, you look for the word “Tablespoons” on the first row, then for the word “Pint” on the first column, and if you go down from “Tablespoons” and right from “Pint”, they’ll meet “32”, so there are 32 Tablespoons in one Pint. Hope that makes sense.

table with volume conversions

Click on the table to see full size

Note: I’ve slightly rounded up a few numbers for simplicity’s sake, and because the difference was so tiny that nobody would be able to measure it with regular measuring tools.

So, what measuring system/units do you use/prefer? Do you use volume or weight measurements for ingredients in cooking/baking?

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5 responses »

  1. yo cocino a ojo…jaja :)

  2. Please don’t get me started on measuring by volume! Especially for baking. Being British I was brought up on Imperial measures, but by weight, not volume — we had big old-fashioned scales with brass weights. Now I use exclusively metric. It’s so straightforward, easy to scale up or down if you want to multiply or decrease the quantity of a recipe. But I nearly always get in a pickle trying to convert recipes given in the dreaded American cups.

    Of course, for a lot of cooking you don’t need to measure at all. A ojo is the way to go! But for baking and preserves I do weigh ingredients because results can be so hit and miss otherwise.

    • Yeah you’re right. You do need measurements for baking, and so many recipes come in cups and spoons that you have to get used to it. I still don’t understand why most people don’t switch to weight; digital scales are almost as cheap as a set of measuring cups and you only need to dump flour or sugar or whatever on them till you get to the right number. Way more simple and less clean-up to do afterwards!
      By the way, old-fashioned scales with brass weights totally rock! Too much of a hassle to use all the time of course… But quite fun to play with.

  3. Yes, I can never understand why people with massive American kitchens stuffed full of KitchenAids, expensive coffee machines and the like baulk at spending a few dollars on a digital scale which will last years :) Measuring flour in cups is SO annoying!


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