comments:
I prefer this solution: Kapro 246 - VPA certified calibration - non-magnetic pocket level less than $8, certified calibration. Tolerance for Kapro's VPA calibrations (Under Accuracy Tolerances): Accuracy tolerance refers to minor and microscopic variations/errors that occur during the production process. It represents a deviation from perfect accuracy for a given length (usually 1 meter or Inch) Professional Spirit Levels have an accuracy tolerance of 0.5 mm/m (0.0005 In/In) while the DIY market sports an accuracy tolerance of 1 mm/m (0.001 In/In). Kapro’s levels offer ±0.5 mm/m (0.0005 In/In) vial accuracy. Kapro’s accuracy tolerance is VPA certified by the Independent German laboratory. Tolerance for iPhones isn't officially disclosed, but here's what Apple says: Use iPhone as a level Use your iPhone to determine whether an object near you is level (parallel to the ground), or how many degrees it varies from level (measurements are approximate). For less than $8, I'll take absolute precision. But if you are OK with being "kinda, mostly close", this works. I am not, turntables are more sensitive than we sometimes like to acknowledge so precision in leveling, being so inexpensive to achieve, is high on my list.