# Thread: Imperial to metric help desperately needed!

1. ## Imperial to metric help desperately needed!

Hi All,

I have embarked on a project where all the measurements are 'imperial' which is what is used in the US etc, but being from the UK I need to buy in 'Metric'.

How or where can I find information on converting imperial hardware to metric.

In the UK, we just don't use inches as its all MM, and inches is confusing the **** out of me.

Or, I wished there were a site where I can buy all my hardware in imperial and just get it all shipped to me in one go without the headache of converting a 5/16-18 nut into a metric one, and something that a british guy will understand.

Can anyone help me?

2. ## Re: Imperial to metric help desperately needed!

Alex, just use a "inches to mm" converter on the Internet...like this one:

http://www.convertunits.com/from/mm/to/inches

As far as tools, us US folks feel the same about metric; therefore, you have to buy and learn to use both measurements. If you don't have two sets of tools (imperial and metric), then you need to invest now. As for the conversion, you could print out a conversion chart like this:

http://mdmetric.com/tech/cvtcht.htm

Hopefully, you'll soon feel better about the measurement systems. We used to hate using metric, but truthfully, it is amazingly easy to understand and use. What could be more simpler than divisions of 10?

BSD Team

3. ## Re: Imperial to metric help desperately needed!

Hi.

But, as for a 5/16-18 what is that. ok 5/16 equals 12.7mm, but a 12.7mm nut doesnt exist in the uk. What does the '-18' at the end of 5/16's mean.

Maybe I sound thick but metric is all 1's, 10s' and 100's etc, its very easy as for working in eighths, sixteenths etc.

Alex

4. ## Re: Imperial to metric help desperately needed!

Alex

I do not know your project. Unless it is a highly stressed piece of fabrication, I doubt that it requires exact metric equivalents in terms of size, stress capacity, thread sizes, on bolts etc. I would just take the nearest metric size that suits/looks ok and/or fits the hole

BTW 5/16 does not equal 12.7mm, it should be 7.9mm. As 1 inch = 25.4mm then 1/16 of an inch = 25.4/16 = 1.5875mm. Therefore 5/16 of an inch = 5 x 1.5875 = 7.937mm

I am old enough to have had to learn both systems

Good luck

David

5. ## Re: Imperial to metric help desperately needed!

Originally Posted by Alex Jarratt
Hi.

But, as for a 5/16-18 what is that. ok 5/16 equals 12.7mm, but a 12.7mm nut doesnt exist in the uk. What does the '-18' at the end of 5/16's mean.

Maybe I sound thick but metric is all 1's, 10s' and 100's etc, its very easy as for working in eighths, sixteenths etc.

Alex
The -18 means there are 18 threads per inch. If you were to rotate the the bolt/nut 18 full turns it will travel 1 full inch. As with metric threads we there are fine and coarse threads for each nominal bolt size, depending on your needs.

6. ## Re: Imperial to metric help desperately needed!

Alex.. I use the DAS Unit Converter all the time for making conversions. It converts nearly everything. I use it for quite a bit of stuff. Also all you need do is type in (for example) 2 inches in cm into google search and google will do it for you.

I like the DAS converter though because you can just update the one and it will do the other without having to retype everything

7. ## Re: Imperial to metric help desperately needed!

Hi All,

Thanks for all your help so far, my head is hurting having been at work all day and now number crunching again lol!

Who can tell me what is the UK equivalent of:

1) #8-32 screw
2) #8 or #10 washers
3) #10-24 screw
4) #6 screw
5) #4 hose clamp

if i know what the above is called in the uk, then i think i can work out the rest!

many many many thanks!

8. ## Re: Imperial to metric help desperately needed!

Now there is the Metric and Imperial version of these screws. They should come in both types in the UK as they do in Canada and we are officially metric as well.

However there is The Metric to Imperial Screw size conversion chart. Here is a UK based hardware store with Imperial screw sized screws Builder Depot

There is also a difference from Self Tapping to Machine screws as well.

I do hope that helps though.
Ron

9. ## Re: Imperial to metric help desperately needed!

Originally Posted by Alex Jarratt
Hi.

But, as for a 5/16-18 what is that. ok 5/16 equals 12.7mm, but a 12.7mm nut doesnt exist in the uk. What does the '-18' at the end of 5/16's mean.

Maybe I sound thick but metric is all 1's, 10s' and 100's etc, its very easy as for working in eighths, sixteenths etc.

Alex
Alex:

The -18 after the 5/16 is the number of threads per inch(TPI). Unfortunately when it comes to nuts and bolts, the two systems are totally incompatible in that you cannot put a metric nut on an imperial bolt no matter how close in size they are.

Without knowing what you're trying to do, the best advice is what a previous poster said; find a source for imperial nuts and bolts on the internet for those situations where you absolutely HAVE to have an imperial part and use metric stuff wherever else you can. Also, for the smaller, wire-size nuts and bolts such as #4-40, #6-32 etc, they can usually be sourced from local hobby stores.

BTW, 1 inch = 25.4mm This is good enough to do conversions between the two systems.

10. ## Re: Imperial to metric help desperately needed!

Alex,

The 8-32 and 10-24 are UNC screw threads used widely in the USA and Canada.
If you go onto e-bay(UK) and search 8-32 UNC you will find a selection of 8-32 UNC screws of all types, the same with 10-24.

All the best,

Andrew

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