# Metric, fractions or decimals. This is about decimals.



## GaryK (Jun 25, 2007)

*Metric, fractions or decimals. This is about decimals.*

This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.

First a quick overview on the different measuring systems.

Here is a good example of the 3 main measuring systems in the world side by side on this Incra Pro scale.










Metric is used by most all the world. You can see it at the bottom of the scale.
1mm and .5mm

Above that is the inch decimal system in 100ths (.010) of an inch.

Above those are the fractions down to 1/64" 
Fractions came about because in the old days it was real easy to divide things in half.
Then in half again and so on. 1/2 - 1/4 - 1/16 - 1/32… Anyone could make a fractional scale.

The area I am going to talk about is decimal inches. They are a commonly used in lieu of fractions.

This is basically 1 inch divided by 1000.

1/1000 of an inch. Represented like this it's a fraction.
You want a foolproof way to convert a fraction to decimal? Divide the top number by the bottom number

Take ½ for example 1 divided by 2 is .5 Just add zeros to get 3 decimal places.
.500 or expressed as 500 thousands. 1/8" would be .125 (thousands) Foolproof.

This is probably the best conversion chart I have found.










Since a lot of people are using CAD programs like Sketchup where you enter dimentions, using decimal makes it real simple. Math is a lot easier also. Try adding 7/16 and 1/8. Adding .437 and .125 is a lot easier.

Once you start using decimals you will see 1/4 written down and automatically think .250 (250 thousands)
When I am writing dimensions on a drawing by hand I will still write 3/4 and .750 on different parts of the same drawing. Old habits die hard. In my mind they are the exact same thing, but when I add 3/4 to something I will always use .750.

So using decimal in a CAD program is easy, but what about measuring something in the real world? Well, there are scales that use decimals. The Incra Pro scale pictured above for example. For things under 6" you can use calipers. I use a dial version since it will never run out of batteries. You can pick them up for less that $20 at some places.

Here's what they look like.










Here's a little video on how to use one.  Video

They are very handy for measuring and marking wood. Set the calipers for what ever dimension you want, press both the sharp ends into your wood and get exact marks.

For things longer than 6" I use a 24" flexible scale. It's called a 5R scale which means that one side has 1/16 and 1/32 and the other has 10ths (.100) and 100ths (.010).
Here are both faces of the scale:


















Most of the time you don't need things super accurate so using the 10ths part is real easy to see and estimate between the lines.

Look at this picture.










Suppose you want to mark 3/8" (.375) or 3/4" (.750). Just imagine there were 100 lines in between each of those numbers and mark either 375 or 750. You can usually mark them within a 1/32". Close enough for most things.

But what if you wanted it marked exactly? Well, look at the scale marked in 100ths (actually they are 10 thousands of an inch apart.) Now you wanted to mark .375. Just put your mark between the .370 and .380 lines. That will be twice as precise as a 1/64".

Have something longer that 24". Then use a decimal tape measure. Here is one I did a review on.

http://lumberjocks.com/reviews/1156

This is just a quick overview to show you about using decimals in woodworking. If you have any specific questions just ask.


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## lilredweldingrod (Nov 23, 2009)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Thanks Gary, I appreciate your reasoning. No arguments form me. Rand


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## a1Jim (Aug 9, 2008)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Good Blog Gary ,I convert to fractions too it seems easy after using them all these years. This should be very helpful for those who are not use to converting to fractions.


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## canadianchips (Mar 12, 2010)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Thanks Gary. I started converting fractions to using decimals in early 80's, I was using a lotus spreadsheet to help me calculate how much solid material I needed to purchase on each job. I had to enter the numbers that my spreadsheet would recognize. I would simply enter the numbers down 2 columns, (say 4 pieces at 1.325 or 6 @1.5 or whatever, at the end of my column it automatically calculated what I needed.It was a very simple spreadsheet, it did save me a lot of time. After seeing some very detailed work on here I realize why micro-measurement can be important. Some projects are borderline ARTWORK, absolutley beautiful !


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## Tikka (May 14, 2007)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Having been educated some 45 tears ago, when I was young and impressionable!, using both fractions and the new fangled metric system, I find merits in both and quite often in my drawings will be in both fraction and metric, which ever is easiest for the measurement (I do not advise doing this) I am trying to record, both systems have there merits, although I cannot say I have ever used decimal inches, except when we get down below 1/64th (machine settings an tolerances) - we are wood workers after all, not machinists.

What did surprise me last year when I was teaching a class of 18+ year old students (Finland, Europe) who only knew the metric system, they did not understand what a fraction was - They knew what a half and a quarter were, but that was as far as it went, they could not grasp the basic algebraic concept- lets hope that fractions are not lost purely to decimals - they are so easy to use and manipulate when you understand the basic principles.

Thanks for posting the chart Gary, I hope this comment does not start any debates on the subject.


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## BertFlores58 (May 26, 2010)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Gary, 
Thanks for this. It is very educational…

Just want to add…

Micrometer…... 
Though we call this kind of caliper as micrometer… it comes into Inches or MM. It has also different ranges.
It works like a dial caliper. Just add sleeve reading and the timble reading (dial scale in a dial caliper) and you will get the actual reading.










how to read….










If anybody wants a vernier scale, it is very easy to make…. 
1. Make a scale on a piece of paper that is less 1 unit of the original scale (for example 1/16). 
2. Divide to desired scale (8 points where 1 point = 1/128 or 10 if in decimal)










3. Use by aligning the 0 point to the last point in the main scale and look for the coinciding line in the vernier to get the actual reading. 









Herebelow is my illustration:


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## TopamaxSurvivor (May 2, 2008)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


I love the vernier scales on my long range sights. Sure makes repeat setting easy when shooting 1,000 yard black powder competitions ;-)

For us 3/4" tape fans, here is one that has decimel on it: 
http://www.amazon.com/Quickread-Power-Return-Tapes-tapemeasure/dp/B004F7MX5Y


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## spunwood (Aug 20, 2010)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Cool stuff guys. Thanks. To think math used to be my most dreaded subject, and now I find it exciting.


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## brunob (Dec 26, 2006)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Thanks Gary,
Very informative and useful.


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## CharlieM1958 (Nov 7, 2006)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


The world would be a nicer place without fractions.


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## Seer (Jun 5, 2008)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


I am not a math wiz but this is what I keep tacked on my wall to help with these:
To get decimal inches divde the Millimeters by 25.4 to get Decimal Inches (This cones in handy for penturning to get the right drill bit)
Fraction to Decimal is the first number Divided by the Second number ie: 15/32 is 15 diveded by 32
I know this is probably what we should know but this little bit has helped.


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## BertFlores58 (May 26, 2010)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Additional tip…. Almost exact equivalent are as follows:

19 mm = 3/4 inches
16 mm = 5/8 inches

1/4 = 6.3 mm
1/2 = 12.7 mm

With the above I easily convert by counting in the tape how many 3/4 I have then multiply it with 20 mm then minus 1 mm on how many I counted.

Example: 1 1/2 = 2×3/4 then it will be …. (2×20 mm) - (2×1mm) = 40 - 2 = 38 mm

On the other hand… I divide the mm by 12.7 mm to get 1/2
Example 30 mm / 12.7 = 2.36 That means 2×1/2 inch = 1 inch + 0.36 inch


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## North40 (Oct 17, 2007)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Good info, Gary! I used to do drafting several hours a day for metalworking. I constantly went back and forth between 64ths and 1000ths. I had memorized all the decimal equivalents to 32nds and knew some of the 64ths off hand. I've forgotten most of them now, but still remember most of the 16ths … so I have a little chart like the one you posted that hangs on the wall by my desk, and another out in the shop.


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## northwoodsman (Feb 22, 2008)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Back in 1996 I was in Hungary working on a project for HfH. We were told to bring metric tape measures with us becuase the materials and blueprints were metric. It was very easy to learn the system. I cannot imagine how hard it would be for them to learn our system of fractions (Imperial) in a pinch. I remember back to my school days when we were taught the metric system becuase "any day now" we would be switching.


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## lew (Feb 13, 2008)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Great info, Gary.

Still learning how to do this, mostly out of necessity because of the digital electronic measuring devices. Still have a little trouble navigating the micrometer, however.

Lew


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## woodsmithshop (Sep 10, 2008)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


I am very glad that I have a calculator that converts for me. lol


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## steliart (Jan 15, 2011)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


I am European and I was not educated in fractions except when I was in elementary school, so it's a bit difficult and time consuming for me to calculate in that all the time. In cases like that when a plan is in fractions, I will use an imperial tape with fractions on it. On the other hand for me the decimal (imperial) system it's more easy to understand and follow as it's closer to the metric concept.


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## Karson (May 9, 2006)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


I use the digital caliper all the time especially when planing wood. I put one on my planer and it's great to be able to go back later and plane a board to the same thickness as before.

Great summation of all of the different measuring scales Gary.

Thanks.


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## Grandpa (Jan 28, 2011)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


I worked in the engineering department of a major oil field service company for 30 years. I have always liked woodworking. I learned to convert all common fractions to decimal fractions many years ago since we drew all drawing in decimal fractions. I used a scale that was in .50ths. In my mind I convert all common fractions when I read a tape measure. This is much easier to add, subtract, divide etc. I do have a tape measure I got at Sears that has 1/16ths on one side of the scale and centimeters on the other side. I would never get another of these. I never realized how often we read a tape on one side and need to transfer a measurement to something else on the other side of the tape. Sure you can convert it but who has the time or wants to go to the bother. I have taped $5 to this measure and thrown it away a couple of time just to have someone mail it back with the $5 missing.


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## JoeLyddon (Apr 22, 2007)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Gary,

A very nice study / subject…

One item caught me by surprise…

*"Try adding 7/16 and 1/8. Adding .437 and .125 is a lot easier."*

I personally found it easier to add the* Fractions:*
1/8 = *2/16*
7 + 2 = 9/16

I did that Super Fast without almost any thought… 

(Now, going to my nearby calculator, 9 divided by 16 = .5625) 

I also added the Decimal… but it took me longer to do so…

Again, thank you for the exercise…


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## Dennisgrosen (Nov 14, 2009)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


thank´s Gary it seems to be a vey good blog
but since I only have time to shim it
Ihave bookmarked it for later 

Dennis


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## jeepturner (Oct 3, 2010)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Thanks Gary for the blog and the thoughts on measuring. Like Joe I had an easier time adding the fractions. Maybe it is because it was a simpler problem than some of the ones we run across. I think that in some instances fractions are easier because they are ratios. Like when I am dividing a side for dados as when I am building a book shelf. Math students benefit from using fractions and so do engineers when designing. They may be calling them by different nouns to suit the situation and usually it is in the form of ratios. I think we do get some benefit using them as we grew up.

The other thing I would like to thank you for is the picture of the scale with the three different gradients. Of course I am going to have to try and find one.

My responses are not always timely, because I can view this site at work, I don't like to sign in. Thanks again for the post.


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## Pimzedd (Jan 22, 2007)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Well done Gary. Bet you background in a machine shop had a big influence in your use of decimals.

I worked in and taught plastics manufacturing. All productions drawings were in decimals. The tolerances were decimals, typically + or - (+/-) .015.

I use similar tools. When I am turning wood, the dial caliper is my best tool. Thanks for the information.


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## TopamaxSurvivor (May 2, 2008)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


unfortunately, all the architectural drawings I have ever seen are in fractions. Sure have seen a lot of mistakes adding all those 1/8s and 1/4s ) I have always wondered why they didn't decimelize? Suppose it had something to do with carpenters being able to grasp the concept )


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## devann (Jan 11, 2011)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Good job on a well written and comprehensive post Gary. Thanks for the conversion chart, I have one on the wall but it only goes down to 16ths. And may I add to your dial vernier caliper comments. The fancy new digital measuring devices ( levels,calipers,etc…) I have purchased over the years have a common flaw. The device is affected by battery power, or lack of it and temperature extremes. With the dial version I can trust the number I see to be correct. And at the $20 price range check and be sure that you get a thumbscrew to lock the setting in place, and that it's made of metal. I purchased a $25 caliper at tha big box hardware store and there was no locking screw and it was made out of a nylon type plastic. The one you have pictured above is the one to buy.


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## ToucheTurtle (Oct 2, 2014)

GaryK said:


> *Metric, fractions or decimals. This is about decimals.*
> 
> This post is not to start any arguments or debates about what is best, but to explain the decimal system to those not familiar with it. Please don't let this blog devolve into an argument about which is best. There are other blogs where that is discussed.
> 
> ...


Sorry, I'm a little late to the party. I love the chart, but wanted to add metric equivalents, so I redid it. Here it is in Excel and .pdf


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