The altitude above sea level of the measuring location has a significant influence on the measured result. If a pipette is adjusted correctly at 1013 hPa (selected volume is the volume at reference temperature of 20 °C), the same pipette will dispense, at an air pressure of 850 hPa (about 1500 m.a.s.l.), an effective volume which is close to the lower limit of the admissible systematic error according to ISO 8655. Pipettes with air cushion should be adjusted and calibrated at the intended location of operation. Electronic pipettes can apply the correction factor in such a way that the pipette balances the error out according to the air pressure or to the altitude above sea level. For this purpose, the user must feed in either the air pressure or the altitude above sea level. For comparison measurements, the measured value can be corrected. For this purpose, however, the exact dead volume and the capillary rise must be known. These two values must be taken into account in the measurement uncertainty budget.