# Thread: Metric and English Conversion

1. Originally Posted by Mark Grotenhuis
How do Europeans buy wood? In America we use the board foot unit which is 12"X12"X1" What do Europeans use? Cubic meters? Board Centimeters? Anyone know?
Lumber is always bough by cubic meter.

Furniture and architectural design elements are usually in millimeters, but in retail the dimensions will be often in centimeters. In practice it doesn't really matter. All you need to do is either add zeros or shift the decimal point. The table below might seem a little scary but in every day life you'll fit in between 0.001 and 1000 most of the time (mili- and kilo-)

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I may be alone on this but I think the Imperial system has advantages for working with middle sized numbers. For very large (for example measuring space) or very small (measuring a molecule), base ten units make computing easy since we use a base ten numbers system. BUT for some things a base 16 system is really nice. For example, I often need to find the center points of various measurements. When a fraction is involved it is often easier to divide a base 16 number than a base 10. Half of one is 1/2, half of 1/2 is 1/4 half of 1/4 is 1/8 half of 1/8 is 1/16. With a base ten system you quickly run into undesirably lone numbers, .5, .025, .0125, .0625. Maybe the best would be to adopt a base 16 numbers system first. Then the "decimal" would align with the "fractional".

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## Cosmopolitan Cocktail

I cannot speak for all of Europe but in Malta we buy wood by the cubic foot, plywood by miilimetre thickness, manufactured and laminated board by Imperial thickness and in 8x4 sheets.

Then we take it home and work mostly with metric size tools and fasteners.

I believe that the UK buys its timber in Imperial sizes too.

Italy has been metric since the year dot. But they still use inches and feet sometimes! I don't know how they buy their wood though and currently don't have a handy friendly Italian to ask.

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Originally Posted by Harlan Barnhart
I may be alone on this but I think the Imperial system has advantages for working with middle sized numbers. For very large (for example measuring space) or very small (measuring a molecule), base ten units make computing easy since we use a base ten numbers system. BUT for some things a base 16 system is really nice. For example, I often need to find the center points of various measurements. When a fraction is involved it is often easier to divide a base 16 number than a base 10. Half of one is 1/2, half of 1/2 is 1/4 half of 1/4 is 1/8 half of 1/8 is 1/16. With a base ten system you quickly run into undesirably lone numbers, .5, .025, .0125, .0625. Maybe the best would be to adopt a base 16 numbers system first. Then the "decimal" would align with the "fractional".
I have not used metric to this point, but I suspect if you were building using the metric system you wouldn't build to "fractions", you would build base ten dimensions. Yes 1/2 of 37cm is 18.5cm or 185mm, but that's still easier than adding or subtracting 16ths and 32nds! Make something with that in mind like you would now.
ex: I want a pc. 3' tall so I can have my shelves about 1' equally spaced. In metric maybe make something 90cm tall with each shelf 30cm. I'm sure our Canadian/European/Aussie.....friends can give better examples.
I feel blessed to have been born in this country, but I find it almost embarassing that we still use such an antiquated system of weights and measures.

5. Hi mark, there are many books available on the subject, I suggest you look at woodworking stores.

http://davelers.com/32mm/Basics/157.html

The above link provides an introduction to the 32mm system.

Basically the system works in increments of 32mm with holes drilled in rows inside cabinets. The distance from the front and back, as well as the bottom are standardised, and all hardware types from hinges to slides fit these holes.

You don't have to drill every hole, I normally only drill one above/below each planned shelf location to allow minor adjustments unless I haven't a clue as to what's going to be stored on the shelves. I like that look much better than an entire row of holes.

The trick is to use metric measurements and design values. The 32mm system is extremely well engineered and once you understand it, you'll find it very fast, efficient and flexible.

You can buy metric measuring tools at any good supplier.

Regards, Rod.

P.S. An internet search will yield more info, however a good book will be a great help.

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Just how "new" do you folks think the metric system is? I may be a little off, but as I recall it was first defined and used in the 18th century. It wasn't widely adopted until the 1960s, but it certainly isn't a recent invention. There's nothing antiquated about the imperial system -- it's just a different system that uses a different set of standards. The standards for both systems are somewhat arbitrary and only apply to everyday life once your brain learns to associate them with something. If you really think the metric system makes sense, ask your favorite european how many Newtons he/she weighs...

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Originally Posted by Jaromir Svoboda
What do Europeans use? Cubic meters? Board Centimeters? Anyone know? I cant wait to tell my local sawmill guy I want my wood in metric and watch the gears in his head grind to a stop.
Cubic meters.[/QUOTE]

Really? Cubic meters seems like such a big unit. For instance, yesterday I bought a board that's 7" by 8' by 1" thick. That's five board feet. If I'm doing my conversion correctly, it would also be .0083 cubic meters. Liters would be a unit more like the usual size of boards. That board would be 8.3 liters. Of course, we'd all be confused when we buy lumber and Coke with the same unit.
Last edited by Jamie Buxton; 12-13-2010 at 2:24 PM. Reason: typo: cubic meters, not cubic feet!

8. Originally Posted by Jamie Buxton
Cubic meters.
Really? Cubic meters seems like such a big unit. For instance, yesterday I bought a board that's 7" by 8' by 1" thick. That's five board feet. If I'm doing my conversion correctly, it would also be .0083 cubic feet. Liters would be a unit more like the usual size of boards. That board would be 8.3 liters. Of course, we'd all be confused when we buy lumber and Coke with the same unit.[/QUOTE]

Jamie, I get 0.39 cubic foot (7" X 96" X 1" /1,728).

I agree, one cubic metre would be a large unit for wood purchases........regards, Rod.

9. Originally Posted by Dan Schocke
. If you really think the metric system makes sense, ask your favorite european how many Newtons he/she weighs...
Well Dan, since the Newton isn't a unit of mass he/she may not know.

However if they know their mass in Kg, they could multiply it by 9.8 m/s to obtain the force they exert on the floor.

It would be similar to asking someone in North America what their weight is in poundals.

regards, Rod.
Last edited by Rod Sheridan; 12-13-2010 at 2:26 PM.

10. Originally Posted by Rod Sheridan
Really? Cubic meters seems like such a big unit. For instance, yesterday I bought a board that's 7" by 8' by 1" thick. That's five board feet. If I'm doing my conversion correctly, it would also be .0083 cubic feet. Liters would be a unit more like the usual size of boards. That board would be 8.3 liters. Of course, we'd all be confused when we buy lumber and Coke with the same unit.
Jamie, and how many board feet do you buy when you buy firewood? Or do you buy them by the cord in the US?
Similarly, when you're buying a single board of the dimensions you stated you'd buy it as a board with the dimensions you stated. The price would likely be calculated in cubic meters because that's how wood is traded, however small the number would be. To you it would still be a board 8 feet long, or 1000 8 feet long boards.

Liters is used for volume (mostly fluid) but is actually not a part of the official SI system. Instead cubic decimeter is used and it is equivalent to 1 liter (1/1000 of a cubic meter). If the unit level is too small or too big you can use one higher or smaller. Similarly, you know that a distance from Berlin to Paris is not expressed in light years or millimeters.

When you buy wood in quantities other than a size of a match then you will definitely buy it by cubic meters. That's how cabinet makers and builders buy. So 100bf a hobbyist would buy is roughly 0.25 cu meters. I think it's quite a manageable number. Also, using the number such as .0083 cubic meters is an attempt to transplant the SAE standard to metric realities, and if correct, the number no more ridiculous than 4.67 b/f

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Originally Posted by Darius Ferlas
...
Liters is used for volume (mostly fluid) but is actually not a part of the official SI system. Instead cubic decimeter is used and it is equivalent to 1 liter (1/1000 of a cubic meter)....
I think you're making my point for me. While cubic decimeter may be an official SI unit, people use liter. They use it because it is a convenient size. Cubic meters is a convenient unit if you're buying some things -- for instance concrete -- but not so convenient if you're buying others -- for instance Coke. Cubic decimeters, while an ideologically pure unit, is too much bother to write out. So folks use liters, whether or not it is official.

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Rod, you hit my point exactly... Kilograms are units of mass, not weight. Weight is mass multiplied by local acceleration due to gravity, and the unit for that in the metric system is Newtons. Pounds, on the other hand, are units of weight, not mass. As human beings cannot sense mass, the kg is somewhat useless as a unit of measure in everyday life.

The poundal is a unit that was really invented to make force calculations simpler in the English system of units, so not sure how that applies here.

13. Originally Posted by Dan Schocke
Rod, you hit my point exactly... Kilograms are units of mass, not weight. Weight is mass multiplied by local acceleration due to gravity, and the unit for that in the metric system is Newtons. Pounds, on the other hand, are units of weight, not mass. As human beings cannot sense mass, the kg is somewhat useless as a unit of measure in everyday life.

The poundal is a unit that was really invented to make force calculations simpler in the English system of units, so not sure how that applies here.
Dan, you're correct, it's been so long since I've used the BE system I forgot that. However I don't think I've ever seen Kg used for anything other than mass.

As for not being able to sense mass, I'm not sure I would agree with that, we only sense force however we can sense mass in both instances where there is gravity and no gravity. If there's no gravity, theres no weight, however we can sense mass by pushing on the object with our finger.

Mass tells us how much matter is in the object, so does weight if we know what the gravitational acceleration is. (fortunately for me I only work on earth so I don't have to worry about that ).

I think in both systems that the average person doesn't understand the units, any quick quiz will demonstrate that, however the metric system is a lot eaier to use.

regards, Rod.

P.S. I was surprised to find that the difference between the Imperial system and the American system was due to updates happening in the Imperial system after the Revolutionary War. I had always assumed that the US had modified their system after the break from England.
Last edited by Rod Sheridan; 12-13-2010 at 4:09 PM.

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Originally Posted by Rick Moyer
I have not used metric to this point, but I suspect if you were building using the metric system you wouldn't build to "fractions", you would build base ten dimensions. Yes 1/2 of 37cm is 18.5cm or 185mm, but that's still easier than adding or subtracting 16ths and 32nds! Make something with that in mind like you would now.
ex: I want a pc. 3' tall so I can have my shelves about 1' equally spaced. In metric maybe make something 90cm tall with each shelf 30cm. I'm sure our Canadian/European/Aussie.....friends can give better examples.
I feel blessed to have been born in this country, but I find it almost embarassing that we still use such an antiquated system of weights and measures.
Its really easier to just work in tenths or 100ths of a mm, just like machinists do. (Machinists work in 100ths of inches as well as SI units).

I'm an electronics engineer, we work in mils and um (micro meters). Circuit boards are in mils, IC's in um, generally. It can cause confusion, but at least it avoids fractions.

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Lets further complicate the question.

If I buy a 2 X 4 I get a piece thaty is nominally 1 1/2" X 3 1/2".
If the metric equivalenty is 100mm X 50mm (1.968" x 3.937") would I get 100mm X 50mm or would I get a nominal size that is equivalent to the 1 1/2" X 3 1/2" American?

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