Instrument calibration ensures accurate measurement without determinate errors.

Calibration is the adjustment of an instrument's measured signal using a standard. For example, an analytical balance that measures mass must be calibrated against a standard weight as a reference.

Here, determinate errors are still possible via air buoyancy, which makes an object lighter in the air than in a vacuum. Any disparity in density between the object being weighed and the calibration weights is resolved by applying a correction to the object's weight.

The relationship between an object's true weight and its weight in the air considers the density of the object, calibration weight, and air under standard laboratory conditions.

The extent of disparity between D_o and D_w directly influences the error in the measured weight.

Spectrophotometer calibration involves the preparation of standard solutions with known analyte concentrations. Measuring them generates a calibration curve used to determine the unknown concentration.