ELI5, How are precision calibration tools, themselves calibrated?

Question

Feels like a chicken and egg senario. Let’s say I get my torque wrench from work sent off to be calibrated, and that’s calibrated with something itself needs to be calibrated, and so on and so fourth. How’s that figured out?

In: 430

Answer 1

Any device used for measuring is calibrated to some extent. Calibration is basically just comparing scales.

The tool used for comparison / calibration itself is manufactured at a higher accuracy level and therefore more exact. Say if you want to measure distance in a 1km accuracy, the tool you use for calibration should be accurate to at least 0.1km. This is why the super accurate devices are used in very controlled environments.

Answer 2

Any device used for measuring is calibrated to some extent. Calibration is basically just comparing scales.

The tool used for comparison / calibration itself is manufactured at a higher accuracy level and therefore more exact. Say if you want to measure distance in a 1km accuracy, the tool you use for calibration should be accurate to at least 0.1km. This is why the super accurate devices are used in very controlled environments.