proper light measuring tool?

I'm running some HLG 100 V2 QB lights in my 2x4 tent and am curious what type of light measureing tool I need for them.

I was looking at the reviews for a best selling 20 bucks lux meter on amazon and someone said they didn't measure led lights very well. my goal is to use it to get the proper distance during growth (to prevent stretch and foxtailing) stages

Cheapest decent meter is probably the sun system par meter. It’s about $150

"Dr. Meter" brand lux device, will give a baseline LUX reading, with white LED. I use one for my BXEB builds.
There are conversion formulas, around here somewhere, for several K values of different white LED emitters, to get an in the ballpark PAR rating.

My local hydro store rents out a par meter.. you should call around

You need to use the lux light meter app and figure it out yourself if you want accurate measurements.

Every light source has a different conversion factor, so even taking measurements on a PAR meter won't yield accurate results.

This thread will teach you how to convert from lux to PAR to ppfd.
https://www.rollitup.org/t/lux-to-par-to-ppfd-conversion-charts.883209/

I picked up a sunsystem quantum par meter wondering how accurate it is. I saw where someone bought two a year apart and they registered off by over 100 micromols. Is there a way to calibrate them?