Use a set of gram weights to see how accurate your electronic scale is. Recognize that most commonly available sets of gram weights will vary in their own accuracy.
However, a kitchen setting does not require ultra-precise measurements. This method eliminates wide discrepencies.
After using a wide variety of solid weights and combinations of them, it seems the accuracy of the measurements for small quantities such as salt and spices, is roughly +/- 0.02 to +/- 0.03. That is well within the tolerance of error in a working kitchen.
The same calibration method should be used — with heavier weights — for non-spice foods.
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