Measuring Inside Dimensions with a Tape Measure

[rgsparber]

Measuring inside dimensions with a decent tape measure is easy. Extend the tape until the end touches one side of the recess while pressing the back of the body of the tape measure against the other side of the recess. Then add the marked offset of the tape measure to the reading on the tape. For example, my tape measure has an offset of 3 inches. I read 28 5/8 inches on the tape.

OK, so that is 3 + 28 5/8 or 30 5/8. Hmmm, something is wrong here.

This error should be obvious as you read it, but it is not always so easy for me to spot when the numbers are floating around inside my fuzzy brain. I needed a less error-prone method.

If you are interested, please, click here.


Your comments are welcome. All of us are smarter than any one of us.


Thanks,

Rick

[DIYer]

Thanks rgsparber! We've added your Tape Measure Inside Measuring Attachment to our Measuring and Marking category,
as well as to your builder page: rgsparber's Homemade Tools. Your receipt:

Tape Measure Inside Measuring Attachment by rgsparber

tags: tape measure

[kngtek]

Hi Rick,
An inexpensive alternative to a tape measure (or your custom measuring device) for exact measurement of inside dimensions is the “EZ Measure Stick” available online from ezwoodshop.com. This is a fantastic little device featuring an expandable, telescoping rod assembly that, as the manufacturer says, allows you to do “No-Math Measuring” of distances especially inside measurements.
Weblink - EZ Measure Stick from EZwoodshop.com
I purchased the “Jumbo Measure Stick” package several years ago and have used it many times for household repairs and woodworking projects (current price usd 29.95) – also good for rough measurements of metal projects. This pack includes a “Mini Measure Stick” extending from 7.6 cm to 21.6 cm (3” to 8.5”) & two “Large Measure Sticks”. One large Measure Stick alone can measure from 17 cm to 116 cm (6-3/4” to 45-3/4”) & two large Measure Sticks (combined via a centre coupling) can extend from 47 cm to 234 cm (18-1/2”to 92-1/4”)
I also purchased a third Large Measure Stick which features triangular-shaped ends for corner-to-corner measurements – Alas, ezwoodshop doesn’t seem to sell these anymore.
On first sight I thought these measure sticks might not be accurate for the following reasons:
a) too flexible, or
b) would slip out of the measured distance either during removal (e.g. from a constrained space) or during transport to the destination, or
c) be unable to accurately mark down the measured distance at the destination.
Wrong on all counts - In reality, the rod assembly is just flexible enough, and the rod-to-rod fit is just stiff enough that the assembly doesn’t move. Also, each end has a “sharp, angled tip” which lies flat and allows marking with either a pencil or a scriber.
Gary Kingsep

[Philip Davies]

I may have put this forward before. Working with learning disabled assistants, I tell them not to use a tape measure. Actually, I usually only use one to elicit approximate dimensions. The EZ Measuring Stick sounds like pinch rods. You can hardly go wrong with pinch rods and the method is easier if you devise a method of clamping. .The first picture shows a pair for testing diagonals on doorways, etc. The second show a short rod or stick to measure the inside of a box.
This is a close up of a clamp on the first picture.

[mklotz]

Yes, nearly every shop will contain a yard stick, a foot rule and a six inch scale (or the metric equivalents for these). Armed with those and a C-clamp (and a powerful scientific calculator capable of adding two digit numbers ) one can calculate the interior length of most anything.

[rgsparber]

The ends of wood rulers can get torn up so don’t read right. I have a steel 2’ ruler with an extra 1/8” on the ends.

Rick

[Toolmaker51]

I like all these solutions, commercial EZ Measuring sticks, the ancient pinch rod, and clamping scales together. The big advantage to Mr. Sparber's device is far greater range, limited only by length of tape measure.
Note; not all tape measure cases are such an easily figured size...

P.S. per your note in post *8. The photo + description of calibrating vs a flat scale makes this all the more worthy. Having an estimated dozen tapes makes adjustable compensation most sensible.

Why so many? I like them magnetic tipped for metalworking, laying out spaces for equipment, wiring, furniture, makes a centering tape ultra handy, the little 12'ers are distributed in vehicles and backpack for haunting surplus yards (imperial & metric in one!), extra-wide tapes for high upright measure needing a lot of tape rigidity, one each on various saws.....not to mention folding rules - engineers in 1/10ths, mason's, carpentry (with the slider).

[rgsparber]

I updated the article to address the problem of odd width tape measure enclosures. You can use a ruler flanking the setup to calibrate.

Rick

[clavius]

I updated the article to address the problem of odd width tape measure enclosures. You can use a ruler flanking the setup to calibrate.

Rick

Rick, I for one really appreciate the fact that you often go back and update your articles based on comments posted here, even those that border on being critical or negative.

And by the way, adding the QR code linking to the article is REALLY clever. Nicely done!

[meyer77]

One method that does not require any thing is to put the end of the tape against one side make a mark at 5",10", 15" or some other number, flip the tape around the other way and add whatever reading you get at marked number.
I like the idea you have but, as murphy's law has it you would be on the third floor and your device would be on the first.