Understanding the Metric system (and other measurements)

While some Americans know the metric system well, others might find getting used to metric a lot harder.  You're not going to be confused forever about it, especially if you are open to changing how you think about measurements.

There are some online tools and conversion charts are readily available (but usually narrow in what they cover, e.g. cookbooks) .  But you're not always going to be able to look things up.  There is one conversion tool you should know about that can help you a lot, and that is Google search.  To convert measurements you type what you want to convert and what you want to convert it to in the search field.  For example, if you want to know what 5 feet is in meters, you type:

5 feet in meters

which yields the result:

five feet = 1.52400 (in bold, at the top of the search result list).

This also works for currency conversion (x usd in gbp) or converting measurements within the same system (x pounds in stones). You can find some of these lesser known uses for Google search here.

I might go into explaining more about the backgrounds of the two systems in a later post, but right now, I am just going to cover switching your thinking to metric.  Some people might do it another way, and others refuse to make the change, but I found my life was easier when I adopted this approach the first time I moved to Europe.  I got a bit rusty in my years back in the States, and I had to make an effort to re-learn the system when I came here.

You can get away with Imperial a bit more here in the UK, but it's increasingly becoming less the case.  Plus, while there is a certain folky appeal to Imperial which is based upon the measurement of everyday objects, metric really does make conversion within the system a lot easier.  But how I am going to help you understand about metric isn't that far off from the spirit on which Imperial was based. 

If you want exact conversions, use an online conversion tool, a formula, or a chart.  This is the case no matter how used to metric you become.

I use this site on BBC for converting the measurements and temperature settings from my US cookbooks.

http://www.bbc.co.uk/food/recipes/converter_index.shtml

I discovered the Google conversion thing a couple of weeks ago! It's great!

I think you're right about switching your way of thinking to be the answer. I'm not quite there, and I'm not sure I'll ever be, to be honest. But especially in terms of air temperature, I find it helps just to have a rough idea of what Centigrade temp would be considered subfreezing, cold, mild, hot or sweltering.

Temperature

There is a formula for converting Celsius into Fahrenheit and one to do the opposite.  You can find it here.  I am going to focus instead on giving you relative ideas about the scale in Celsius when it comes to weather, particularly the range you should expect in the UK.  And, yes, these relative ideas are a bit subjective, but it will help with perspectives.

-10°C=14°F
-5°C=23°F
0°C=32°F
5°C=41°F
10°C=50°F
15°C=59°F
20°C=68°F
25°C=77°F
30°C=86°F
35°C=95°F

Keep in mind that British weather tends to be damper than the weather in most of the US, so you might feel colder at a higher temperature in the winter and hotter at a lower temperature in the summer.

Cooking:
For the most part, I found in using US ovens, we baked mainly between 300°F and 400°F.  Most cookbooks have conversions, and you should use them or another conversion method, especially when baking rather than roasting, as baking requires more exact measurements in everything, including oven temperatures.  However, to give you a general idea, 325°F is around 160°C (not exact), 350°F is around 175°C, 375°F is around 190°C, and 400°F is around 205°C.

I've not seen UK ovens with Fahrenheit measures because I believe they used gas marks, which I am not going to cover here. 

Weight

Most British people will give you their weight in stones the remainder in pounds.  A stone is 14 pounds.  This, of course, isn't metric.

The metric system uses grams as the basis for weight.  1000 grams is a kilogram.  In practical use, you just need to keep in mind that a pound is just under half a kilo (around .45 of a kilo or around 450 grams).  So when shopping, if you see a package that is 500 g, know this is just over a pound.  A kg, of course, would be just over 2 pounds.

It gets a bit more difficult when you have an item that you know is less than a pound and you want to quickly guess the metric weight.  Say you have an apple which you know is about a quarter of a pound.  You can guess that's a little over a tenth of a kg or a bit more than 100 g.

It takes practice, but the more you do it, the less you will rely upon the US system, and the more you will think more in metric measurements.  Of course, many of us can never give up Imperial, particularly when we rely upon cookbooks from the States.  But I promise, with practice you will soon have a way to spatially understand approximations in both systems.

Distance and length

Meters are the measure here.  Either you're going to be using a division of them, or a multiplication of them, just like grams in weight.

A lot of British people still use miles for distance.  I found that kilometres were the easiest thing for me to get my head around, but I also have never driven extensively using km (a little in CA). I am sure that would make a difference, particularly in long distances.

A mile is about 1.6 km.  A km is about .6 mile.

In shorter distances, a meter is very close to a yard, but I don't think we even use yards much any more in the States.  It's probably because these two measures are so close, meters have been substituted for yards.

So, a meter is just over a yard.  There are 3 feet in a yard.  There are just over 3 feet in a meter (about 3.3).  So, when someone says something is a meter away, think about a yard or about 3 feet.

Average man=6 feet=1.82 meters

When we get below a meter, metric uses centimetres and millimetres.  There are about two and a half cm in an inch.  A medium sized blueberry is about a cm in diameter.  A mm (a tenth of a cm) is about the same as the thickness of a CD.

Volume

Because we have been using litres for a while for sodas, most of us have an idea about litres.  It's around a quart, or exactly a 1 litre Pepsi bottle.    However, that doesn't help if you're about to fill up your car with petrol.  There's about four and a half litres in a gallon.  Most drinks are sold in metric units (ml, l) but milk is usually sold in pints (not metric, of course). For some reason, I've found this harder to get used to than metric.  I am forever correcting myself about it. "Honey, pick up a gallon...err a really big bottle of milk on the way home please."

Anyway, back to metrics.  A cup is about 236 ml.  Most liquid US measuring cups will have both marked.  100 ml is a popular nutritional label demarcation, and that's a bit under a half a cup.  5 ml is about a tsp.  15 ml a Tbs. 


Helpful website

A helpful website to not only give you a good idea about how the metric system works, but gives you real world examples of the measurements is Think Metric.

Temperature

There is a formula for converting Celsius into Fahrenheit and one to do the opposite.  You can find it here.  I am going to focus instead on giving you relative ideas about the scale in Celsius when it comes to weather, particularly the range you should expect in the UK.  And, yes, these relative ideas are a bit subjective, but it will help with perspectives.

-10°C=14°F
-5°C=23°F
0°C=32°F
5°C=41°F
10°C=50°F
15°C=59°F
20°C=68°F
25°C=77°F
30°C=86°F
35°C=95°F

Keep in mind that British weather tends to be damper than the weather in most of the US, so you might feel colder at a higher temperature in the winter and hotter at a lower temperature in the summer.

I am learning to think in Celsius, but the thing that helped me "translate" C to F was this little formula I learned from my Uncle Charles.  Double the Celsius temp and add 30 and you get the "ballpark" Fahrenheit temp.  For instance, 20^c   is 20 + 20 +30 = 70^f.  It is not exact , but is close enough for me to know what to expect when I hear the weather predictions.  After a while, 20^c started having a meaning for me, without having to make the calculation.

Something I did in Tim's kitchen was I hung conversion charts for everything (temperature, volume, weight) on the inside of the kitchen cabinet where it was easily at my reach while cooking.  After about a month, I noticed I was going to the charts less and less and was remembering the conversions or able to just do them in my head if I had a US recipe to work with.  What helped me was looking at the conversions and memorizing them that way, as opposed to trying to remember math equations or constantly firing up google.

My Fahrenheit to Celcius conversion is something like this:

> 30°C - never gets that hot here, so why bother? 

25°-30°C - now we're talking = south Florida temps (aaaahhhhh) but very infrequent here 

15°-20°C - Florida winter = English summer (chilly) 

5°-10°C - COLD! 

< 5°C - cannot deal 

My Fahrenheit to Celcius conversion is something like this:

> 30°C - never gets that hot here, so why bother? 

25°-30°C - now we're talking = south Florida temps (aaaahhhhh) but very infrequent here 

15°-20°C - Florida winter = English summer (chilly) 

5°-10°C - COLD! 

< 5°C - cannot deal 

LOL, love it Mrs R!

Volume
Because we have been using litres for a while for sodas, most of us have an idea about litres.  It's around a quart, or exactly a 1 litre Pepsi bottle.    However, that doesn't help if you're about to fill up your car with petrol.  There's about four and a half litres in a gallon.  Most drinks are sold in metric units (ml, l) but milk is usually sold in pints (not metric, of course). For some reason, I've found this harder to get used to than metric.  I am forever correcting myself about it. "Honey, pick up a gallon...err a really big bottle of milk on the way home please."

A slight correction: there a 3.785 litres in a US Gallon as there is a difference between US and Imperial measurements.

Yeah, I knew there was a difference, but I assumed Google was using US gallons for some reason. My cup/ml conversion may be wrong as well as the relatively unused Imperial cup is different than the US one IIRC.  Any corrections are welcome.  It gets more complicated when you factor in some of the Imperial units still in use in the UK compared with the US measurements.  Best way to deal with it IMO is when it really matters (baking, cooking) know which system the recipe is using and use the measuring cups from that system.  If you're still in the States and plan to use US cookbooks, bring over the cups and spoons (preferably ones with ml on them as well).

I've found I weigh ingredients here a lot more often than I used to and would love to see it become more of the standard in recipes, at least with dry ingredients.

ETA:  I sort of been meaning to write something like this, and never got around to it.  I sort of did it spur of the moment, and I've found the history of measurements really interesting, especially the variations just in the British Isles.

I've not seen UK ovens with Fahrenheit measures because I believe they used gas marks, which I am not going to cover here. 

Older electric ovens had Fahrenheit dials, so if you pick up recipe books from the 1960's or earlier you'll find that they always give Fahrenheit temperatures.  The changeover to centigrade on appliances took place mostly during the 1970's.

But yes, gas ovens always used to use the "mark" system, in which there's a 25-degree (Fahrenheit) difference between each setting.  Here's the conversion for anyone who needs it:

Gas mark = Degrees F

1/4 =  225
1/2 = 250
1 = 275
2 = 300
3 = 325
4 = 350
5 = 375
6 = 400
7 = 425
8 = 450
9 = 475

A lot of British people still use miles for distance. 

I think it would be more appropriate to say that most (almost all, in fact) British people still use miles for distances.  Despite the fact that metric has been mandated in most fields now, feet, yards and miles are still the official measurements on roads.  Distance signs on roads are in miles, speed limits are in miles per hour, and shorter distances (e.g. advance warning of a hazard directly ahead) are required to be signed in yards.  Height & width limits are required to be signed in feet & inches.

Thanks Legs. Think a lot could make use of your work. Though I've always been conversant with metric since living in Germany

There are a few measuremenst that I don't think I'll ever lose:

Miles on the road
Stones for pesonal weight
feet and inches for height
Yards for the golf course