Why the end of your tape measure jiggles

[Marshal Mo Hare, SASS #45984]

The rivets are loose and the holes in the tab are just long enough to allow the it to move back and forth a distance equal to the thickness of the vertical face of the tab.

This way, if you are measuring an outside distance, as in the upper example below, the tab extends so that the measurement starts from the inside edge of the tab.

If you are measuring an inside distance, as in the lower example, the tab is pushed in and the measurement starts from the outside edge of the tab.

Edited January 16 by Marshal Mo Hare, SASS #45984

[Eyesa Horg]

Somehow I've known that for like ever!

[John Kloehr]

1 minute ago, Eyesa Horg said:

Somehow I've known that for like ever!

Yes, and it the reason to never let the tape snap back closed at high speed; the rivet holes will get stretched and add error to outside measurements. If the holes are stretched, than a piece cut to fit inside a space will be too long.

[Marshal Mo Hare, SASS #45984]

I recall being taught to always start my measuring at the one inch line because of that jiggle.

[Eyesa Horg]

It's surprising how much 2 different tapes can be off. I've got a nice stainless 100' Lufkin that is off by 2" compared to my steel 100' Stanley at full measure.

If you have some yelling measurements to you, compare your tapes to determine error margin! A sixteenth to an eighth can matter!

[John Kloehr]

19 minutes ago, Eyesa Horg said:

... compare your tapes to determine error margin! A sixteenth to an eighth can matter!

1st thing each day for an experienced crew.

[Alpo]

Customer I used to have. Their QA guy had two calibrated steel tapes. One for inside measurements. One for outside measurements. And they were sent off for calibration every year. Had stickers on them.

 

Kenny took his job seriously.

[Eyesa Horg]

And fiberglass tapes are a whole different animal!! Amazing amount of stretch at long length!

[Abilene Slim SASS 81783]

1 hour ago, Eyesa Horg said:

It's surprising how much 2 different tapes can be off. I've got a nice stainless 100' Lufkin that is off by 2" compared to my steel 100' Stanley at full measure.

If you have some yelling measurements to you, compare your tapes to determine error margin! A sixteenth to an eighth can matter!

I have a number of tape measures, but for that reason, I make sure to use the same one for the duration of a job.

[Eyesa Horg]

I have several Stanley one inch 25 foot tapes and only two are exactly the same on extreme 2 are different by a sixteenth at 8 feet! 

[Crazy Gun Barney, SASS #2428]

At one shop I worked at, The QC manager kept having the same issue.  They calibrated and put a sticker on all measuring devices once a year.  Took him a while to work thru the whole shop checking everything including yo-yo's (tape measures).  He would find guys using tapes that didnt have the wiggle.  he would ask (thru an interpreter) and the user would say that the rivets were loose so he tightened them.  QC guy explained why they loose and give him a new tape.  He checked back in a few days just to be sure and the guy had "fixed the loose end" again.

 

On the other end of the spectrum, the guy on the shear had accidently sheared off the end of the tape.  He had the tig guy (a very talented welder) weld it back together.  It was done so well that the tape still completely retracted, and it was still in calibration!  The QC guy issued him a new tape anyway and mounted the welded one on the wall in his office!

[Abilene Slim SASS 81783]

When I used to do home renovations with a partner, he & I would use the caveat “by my tape measure…” which would suffice for most everything. A 1/16” or so here and there wasn’t that critical. When it was, like cutting tile, we used a common measure. 

[Eyesa Horg]

Wow, that's some talent to weld a tape back together and have it retract. I'm impressed. But then I weld like chicken poop on quarter inch stock lol.

[Abilene Slim SASS 81783]

Last time (and only) time I tried welding, I had so many craters it looked like a moonscape. 

[Crazy Gun Barney, SASS #2428]

1 hour ago, Eyesa Horg said:

Wow, that's some talent to weld a tape back together and have it retract.

Juan was an excellent welder!  Well trained and certified.  We used him for some of the govt contracts we built for that required full traceability.  Our standard stuff was mostly welded by MIG (booger guns).

[Calamity Kris]

Believe it or not, dressmaking tape measures have to be replaced every couple of years as well.  The plastic can stretch over time too.  I will occasionally check mine against a flat dressmaking ruler to check their calibration.  If they are off, they go in the trash and I buy a new one.  Close tolerances matter in sewing also.

[Cypress Sun]

1 hour ago, Abilene Slim SASS 81783 said:

Last time (and only) time I tried welding, I had so many craters it looked like a moonscape. 

 

I was an electrician for 45 years.

I welded on occasion, never on purpose though.

[Wallaby Jack, SASS #44062]

2 hours ago, Cypress Sun said:

 

I was an electrician for 45 years.

I welded on occasion, never on purpose though.

 

  ...... been'd there, do'd that

[Forty Rod SASS 3935]

7 hours ago, Marshal Mo Hare, SASS #45984 said:

I recall being taught to always start my measuring at the one inch line because of that jiggle.

That's what Dad taught me, too.

[Eyesa Horg]

3 hours ago, Cypress Sun said:

 

I was an electrician for 45 years.

I welded on occasion, never on purpose though.

I'll tell ya a staple gun set down in a panel you thought was dead can get startlingly! And bright! 

[Pat Riot]

I grew up using a tape measure and I learned to use it properly. 
When I was inspecting new trains being built for our rail systems I insisted on calibrated tape measures and part of that calibration was the precision of the end piece. 
One dipstick with his favorite tape measure he found in “gramma’s pitcher hangin’ box” can really screw up a slew of interior melamine panels…

That idiot lost his job and cost the train builder tens of thousands of dollars. 

[Crooked River Pete, SASS 43485]

8 hours ago, Marshal Mo Hare, SASS #45984 said:

I recall being taught to always start my measuring at the one inch line because of that jiggle.

That's Why the most common error in industry is one inch. We used to start at 10 inches, easier to see before you cut. 

[Alpo]

When Daddy did carpentry he did not use a tape measure. He had two folding rules - one inside and one outside.

 

The inside rule had a sliding brass rod in it, so you could measure less than the 8 inches the folding piece was.

 

 

All this talk about calibrated tape measures got me thinking about that. And everyone knows when you're trying to do an inside measurement with a tape measure it tells you on the tape case how long it is. So you can just add that on to the end of what your tape says and have the correct measurement. Everyone knows that.

 

So I just went and put a caliper on my tape measure. It says quite plainly on the tape case that it is 3 inches.

 

The caliper says 3.042. that's between a 32nd and a 16th of an inch long. So much for precision.

[Calamity Kris]

19 hours ago, Pat Riot said:

One dipstick with his favorite tape measure he found in “gramma’s pitcher hangin’ box” can really screw up a slew of interior melamine panels…

That idiot lost his job and cost the train builder tens of thousands of dollars. 

 

When I worked in the shop building aircraft interiors, they would not allow us to use retractable or vinyl tapes in measuring our tolerances.  We had to use solid aluminum or steel rulers and yardsticks.  If we brought one in from the outside, it had to be certified before we could use it in the shop.  

[Stump Water]

On 1/16/2026 at 8:17 AM, Eyesa Horg said:

Somehow I've known that for like ever!

 

Yep.

[Stump Water]

18 hours ago, Alpo said:

When Daddy did carpentry he did not use a tape measure. He had two folding rules

 

Yep. 

 

Dad had a tape measure.  Had a bakelite case and was only 5 or 6'. 

 

He always used a folding rule.  

[watab kid]

i always knew this but always questtioned just how accurate they were in that mode [push/pull] i dont trust their quality control of those rivets , yet ive used mine for decades now and most everything has worked out fine with a couple rare exceptions , im used to old school drafting instruments and scales with really fine lines i can no longer see without a magnifyer v

[John Kloehr]

Plus or minus 1/16" is fine for rough framing a house. Supposedly an 1/8" is fine too, but any experienced contractor should not be that sloppy, that is a full saw-blade width. Most tape measures are fine. Not all, though:

 

 

For something like trim work which will be stained (not painters putty and paint), it can get down to "lose the line" or "leave the line," instead of the default splitting the line.

[Colorado Coffinmaker]

 

The High End Cabinet shop I worked for required ALL tape measures to be checked against a precision straight edge.  EVERY Monday, Wednesday and Friday.  If your tape failed, it went into the trash and you were "gifted" a new, certified one.   I still check ALL my tape measures here at home against a precision solid steel rule.