Tape Measure Accuracy (class 1 / class 2)

Hi everyone, I’m about to try out @Joshua and @madgrizzle’s HoleyCalibration system and want to minimize my sources of measurement error. To that end, I want get a more accurate tape measure. While calibrating my other CNC machine I discovered that my meter stick and my tape measure disagree about how long a mm is, even over the span of 500mm.

I’ve read about Class 1 and Class 2 tape measures. What are folks here using for their tape measure? Is Class 2 enough for all practical purposes or is it worth getting a Class 1? Where do you buy them? An Amazon search for “Class 1 Metric Tape Measure” doesn’t come up with much. Any specific recommendations?

I searched around a bit and didn’t find a good canonical thread about good tape measures so I think we could build up that base of knowledge here.

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see the topic “in search of accurate measurements”, it actually has a nice
discussion of tape measure accuracy in it

I like this class 2 tape measure
https://www.rockler.com/fastcap-procarpenter-standard-metric-tape-measure as it
has both imperial and metric markings.

the difference between class 1 and class 2 are:

  1. error on the end (handled by my jigs)
  2. .1mm per m of allowed error

so the total error in our measurements is going to only be around 0.1 to 0.3mm
different between the two, I don’t think that is going to matter.

David Lang

Thanks @dlang for the recommendation and for directing me to your post. I’ll also print your tape measure vernier thing and try it for HoleyCalibration that you mention there!

I own one and love having a writable/erasable area and pencil sharpener built in.