My messed up imperial / metric head

I love old school units of measurement. Take the furlong - the distance a team of oxen could plough before resting. The acre was defined by the furlong. Many of the units had real practical value. I was born the year the UK adopted the metric system, so I grew up in a hodgepodge world, where I drove miles and drank pints (proper ones, not the little ones the US use!). I climbed mountains measured in metres and measured my runs in 1km splits. I knew that when the temperature was below zero, then water would freeze but when my dad talked about it being 80 it was going to be a hot day. And in cooking I use grams, kilos, millilitres and litres, sometimes pounds and ounces but never cups. At school, university and my career as an engineer it was all metric.

This week I started a three year renovation of an old property in Dutchess County, New York. I spent a day collecting data, all in millimetres - the length, width and height of every room. I then spent two days drawing up room plans and elevations. I’ve now come to the conclusion that this was a mistake as everything here is still feet and inches. I’ve never done any calculations using feet and inches and it’s making my brain hurt. It’s base twelve with fractions. I’m a maths nerd and I’m making too many mistakes. Addition and subtraction is taxing, multiplication nearly impossible. What do people in the US use? Are there special calculators or apps that I don’t know about?

Having lived my life in the US almost my whole life except for the year we spent in Mexico, I only know inches and feet.

I have a twelve-inch ruler like kids use in school, or at least used to use in school.  One side is inches and the other side is metric. I never use that unless I am buying something from China.

I have a yardstick that is 3 feet long.  I rarely look at it except when sewing.

I also use a calculator.

Like the example, I gave in another post.  Lumber comes in 8-foot, 10-foot, and 12-foot pieces if I am remembering correctly.

The lumber some in different widths, like 2 inches by 4 inches or 6 inches, etc.

My suggestion would be to take those drawings and trace them on another sheet of paper without measurement.  Then add US feet and inches.

I also suggest looking at one of the big box store websites before going shopping to make sure everything is available in the sizes on your shopping list.

Best wishes for this job and I hope some of this was of value.  

Also I forgot to mention about folding rulers if you will be measuring large areas by yourself.  Ours is the wooden kind like this:

There maybe some that are both inches and metric:

https://www.amazon.com/Stabila-1607-Wooden-Folding-200Cm/dp/B000Y8PXRI/ref=sr_1_105?keywords=folding+ruler&qid=1650232941&sr=8-105

I'm so used to feet and inches that I don't even know what the problem is :(  

One huge issue is that they've shrunk some things so they aren't the stated size.  Most common thing is that 2x4's aren't 2" by 4", they're 1.5" by 3.5".  And it doesn't scale up exactly.  A 2x6 is 1.5 x 5.5 but a 2x10 is something like 1.5 by 9.25.  They 1.5" dimension stays the same luckily.  Most boards are actually a bit long so when you get an 8' long 2x4 it's often a smidgen longer.  So plan to cut them all to length even if you think they're the right length.

Plywood also comes in thinner sizes.  Usually it's listed somewhere as you buy it but 1/2" plywood is usually 1/16" thinner or so.  Usually not a big deal for housework.  It's a much bigger deal for furniture making or cabinets.

I don't think I do much multiplying in construction.  Maybe for figuring roof or floor square footage.  For that I just round up to the next half foot or full foot since there will be waste anyway.  If I think it'll be close, I'll sketch up the sheets of plywood and how they land on the floor in the hopes that the end of one run will do the start of the next and I save some waste.  Lots of materials are specified in square feet (flooring especially).

I don't think there's anything in US home construction that is in metric so definitely measure in good old fashioned feet and inches.  Usually you don't need to measure more precisely than 1/8ths of an inch.

That's my brain dump for now...  Good luck!

I'm with you. I measure in inches and feet, but, despite being American, I hate working with base 12.  5 feet 3 and a half inches divided into even thirds is... Oh poop.

Wrenches and sockets  make me utterly insane. I have to do the fractional math every time . I like metric tools!

For base 12, as far as converting measurement, I cheat and do a search on the net and it comes up an answer. Otherwise I simply stomp my way through it. If I'm doing something like the example above I put it all to inches, divide, then convert it back to measurements I can tell others. And I often use my own words when I work alone, 1 foot nine inches and a shred and a half, minus the saw kerf, put it right there.  

Try this conversion calcuator.

As far as what do people in the US use ... I grew up with the Imperial system but exclusively used metric in the electronics field.  I remember my grade school teachers saying the US would be totally converted to metric system in the not too distant future. Didn't happen. Not sure why except maybe people are resistant to change. The metric system is so much easier. No need to take socks off:)

I use all the usual American measurements, except when baking, portioning food for Charlie, etc. Like Mike, I use an online calculator to figure things like Fahrenheit / Celsius, etc.

Calculated Industries makes a number of calculators for the construction industries that works well with Imperial units and their fractions. Some of their models can also convert to metric. You can buy physical calculators or phone apps.

Calculated Pro App

Their most basic model can convert to meters and back. webpage

Thank you for some very useful insight. Mostly I’ve been trying to do sums like 13’ 8 3/4” - 2’ 9 5/16” - 5’ 1 7/8” . . . Which I now realise can be rounded to 13’ 9” - 2’9” - 5’ 2” and even that still makes my head hurt!

That looks like a great App Jeremy - thanks.

Jeremy VanGelder wrote:Calculated Industries makes a number of calculators for the construction industries that works well with Imperial units and their fractions. Some of their models can also convert to metric. You can buy physical calculators or phone apps.

Calculated Pro App

Their most basic model can convert to meters and back. webpage

I checked out the App and it’s a pretty expensive rental / subscription. I like the look of their physical calcs. On the plus side, the App page suggested Home Improvement Calc for $1.99 and it does exactly what I want.

Edward Norton wrote:Thank you for some very useful insight. Mostly I’ve been trying to do sums like 13’ 8 3/4” - 2’ 9 5/16” - 5’ 1 7/8” . . . Which I now realise can be rounded to 13’ 9” - 2’9” - 5’ 2” and even that still makes my head hurt!

That looks like a great App Jeremy - thanks.

If you plan to do math(s) with Imperial measurements, it can be easier to keep it all in inches. 8'9-1/2" as 105-1/2, for instance. You skip the base 12 part, leaving the just the fractions to sort out.
If adding and subtracting fractions is tough (helps to use least common denominators) you could also try working in decimal inches which is how (old school) machinists (only in the USA) work. So, 8'9-1/2" becomes 105.5".

The quarter inches are easy 0.25, 0.50, 0.75 (same as dollars)... the eighths 0.125, 0.375, 0.625, 0.875... the sixteenths 0.0625, 0.1875, 0.3125, 0.4375, 0.5625, 0.6875, 0.8125, 0.9375... You may notice a pattern in the numbers, and it continues to repeat (or maybe it rhymes?) as you go further to 1/32nds, and 1/64ths, both of which you are unlikely to use. But that pattern is a help, since any sum is also going to be one of those numbers, and you can commit some to memory. (Three decimals is overkill for carpentry, and rounding to two decimals is not going to make any difference, other than that pattern of numbers gets a bit muddied)

A friend's dad (who is British) used a combination Imperial/Metric tape measure, and just chose to use whichever scale had a marking at the correct spot for any given measurement he was taking. Which is fine for your own work, but when you go to the store to find a board, it's in feet/inches only. Mike Hassl is right about the "nominal sizes" being different than the actual dimensions, and in an old house renovation, you may find "full 2x4's or 2x10's" for example, which can present both problems and opportunities. You may also find yourself looking for architectural salvage, if you are trying to match doors/windows/trim/hardware to what's in this old house of yours.

Mike Haasl wrote:
One huge issue is that they've shrunk some things so they aren't the stated size.  Most common thing is that 2x4's aren't 2" by 4", they're 1.5" by 3.5".  And it doesn't scale up exactly.  A 2x6 is 1.5 x 5.5 but a 2x10 is something like 1.5 by 9.25.  They 1.5" dimension stays the same luckily.

In the UK I know that the stated size is for unplaned timber, so the planed timber is always a bit smaller than you think.

I grew up in the US, in the late 70s I remember my first-and-second-grade teacher being really gun hoe, learn metrics the US is going to change! I guess we gave up on that idea huh?  See picture of fun memento from the Iowa State Fair in the late 70s.

But I've lived in Mexico for over 20 years now. I'm pretty good with the metrics I use regularly, short distances, up to 5 kilos, Celcius, for longer things I just ask google.
Seriously you don't need a fancy conversation app, just say--180 cm in inches, to google either in voice or text and it tells you the answer, right there, you don't even need to click on a link.

Historical fun: the late Martin Gardner's 1952 book "Fads and Fallacies" notes the fervor whipped up by devotion to a system of measurement.

An "International Institute for Preserving and Protecting Weights and Measures" was organized in Boston, in 1879, at a meeting in Old South Church. The purpose of the society was to work for the revision of measuring units to conform to "sacred" Pyramid standards and to combat the "atheistic metrical system" of France. President James A. Garfield was a supporter of the Society, though he declined to serve as its president.

A periodical called "The International Standard" was published during the 1880's by the Ohio Auxiliary of the Society. The president of the Ohio group, a civil engineer who prided himself on having an arm exactly one cubit in length, had this to say in the first issue: "We believe our work to be of God ... we proclaim a ceaseless antagonism to that great evil, the French Metric System ... may our banner be ever upheld in the cause of Truth, Freedom and Universal Brotherhood, founded upon a just weight and a just measure, which alone are acceptable to the Lord."

A later issue printed the words and music of a song, the fourth verse of which ran:

Then down with every metric scheme taught by the foreign school,
We'll worship still our Father's God, and keep our Father's rule!
A perfect inch, a perfect pint, the Anglo's honest pound,
Shall hold their place upon the earth till time's last trump shall sound!

Yeah, fraction conversion to decimal works fine. 1/2 = .5  1/4 =.25 1/8 =.125.
Remembering most building is based on factors of two. To minimize wasting material stick to the notion that walls stretched out in a linear fashion should add up to a round number divisible by two, on the outside measured walls. 12 by 16...24 by 32 sort of thing, in feet.

It’s great to pencil things out on a sheet or two of graph paper. Draw it out, remember paper is cheaper than lumber. I spent hours doing this with an architect ruler when I couldn’t do anything else. Referencing how to books from a bygone era when people  did build their own houses. I’m pretty sure that stuff can be found on line....