A2LA is the largest and most well-recognized accreditor of calibration laboratories in the United States.

The A2LA Calibration Laboratory Accreditation Program services customers in all metrology industries and provides opportunities for accreditation in virtually every field of measurement. Calibration laboratories in our accreditation program support testing laboratories, other calibration laboratories, industry, manufacturing, government and regulatory bodies and all other sectors in which measurement confidence is critical.

Accreditation in our calibration program ensures a quality assessment with technical experts who have experience in the field of measurement being assessed, resulting in greater customer confidence in measurement results.

Program Requirements


  • ISO/IEC 17025 General Requirements for the Competence of Testing and Calibration Laboratories
  • A2LA Calibration Program Requirements
  • Optional: ANSI/NCSL Z540-1 and ANSI/NCSL Z540-3*
*These optional accreditations are only offered in combination with ISO/IEC 17025. These are generally only pursued when a calibration laboratory's customers specify compliance to the additional requirements of these standards. 


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