![](https://imgur.com/QhEgi1f.jpg)
Until you check them all agin' yer cheap Chinese digital calipers, you'll never know which is right... ![Evil >:D](https://www.eevblog.com/forum/Smileys/default/xevil.gif.pagespeed.ic.tdrs7Uj5gu.png)
I had to dig out -- while on vacation, so selection is limited -- my rulers / measuring tape / not-cheap not-chinese calipers and compare them.
A Bundeswehr surplus steel ruler, a "Co-Tech" China steel ruler, the 6" ruler from a iFixit "Professional Toolkit", a vintage "Mako by Stålex" steel caliper, analog, a Hultafors measuring tape (EU Class II, so cheap) and a Hultafors EU Class III folding wooden meterstick were extracted from the toolcase.
The steel rulers and the caliper agree that the iFixit one is crap. I estimate it to be off by 0,4-0,6mm over 150mm. The others are impossible to gauge any diff by eye, so are deemed to be in agreement. The measuring tape and the folding stick are off a bit less than the iFixit one, with the tape holding a slight edge to the stick. The stick, across one joint, is off by a guesstimated 0,3mm over 300mm against one of the good steel rulers. It being EU class III this is within the specifications. Not bad for
a piecetwo pieces of wood. The tape is a advertising one, so not the full professional quality, only quite good. Tape is made in the UK!
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif.pagespeed.ce._hfWAz_QHO.gif)
Conclusions?
No surprises. Steel rulers often are the best alternative if you can't measure with a caliper. I do not carry any plastic ones in my kit so can't compare with them. Tapes come in various qualities -- I've got a "Talmeter" at home, which is not a marketing product, so will try to remember checking it too. Somewhere I've got a Pentair / Schroff HE/TE steel tape, and also a Knürr one.
The iFixit one being crap is not surprising either.
Tape and stick are for carpenters. Their desired precision "decade" is "one floor, one foot, one inch" so a basic error of 0,1% is not a problem for them.
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif.pagespeed.ce._hfWAz_QHO.gif)
Measurement -- it's a rabbit hole lined with broken hopes, products and assumptions in so many ways.