Measurements are a fundamental part of our everyday lives since they are found in almost every one of our activities. All products are bought and sold after the performance of measuring processes, whether it be coffee, water or electricity, and this has effects on our personal economy. The radars (speed cameras) used by police, for example – which have economic and criminal consequences – are also subject to measuring. Hours of sunshine, clothing sizes, percentage of alcohol, the weight of letters, local temperature, tyre pressure... it is virtually impossible to describe any activity without mentioning metrology.

Logically, then, correct measurements are of utmost importance for the economy, for enterprise, and for the population in general, helping not only to organise business transactions but also allowing products and services to be exchanged on a global scale.

The development of metrology accords multiple benefits to the industrial world:

  • It facilitates the development of a harmonised system of measurement.
  • It promotes the development of tests needed for a competitive industry.
  • It equips the industry with the necessary measurement tools for the investigation and development of certain fields and to better define and control product quality.
  • It facilitates the exchange of technical and scientific information.
  • It allows for greater international product standardisation in general.

ENAC acts specifically in this sector in two major areas: calibration and legal metrology, although metrology plays a key role in almost any activity in the other sectors.


Companies need to ensure that the results they obtain from their measuring equipment are correct when used in key activities such as controlling process variables, assuring the quality or safety of their products, processes or services, or obtaining data required for analysis and important decisions.

Component ageing, temperature changes, the mechanical stress supported by the equipment, etc. leads to the gradual impairment of its functions. When this happens, measurements and tests become less accurate, which affects both the design and quality of the product.

It is therefore essential to have technically competent calibration services to meet the metrological needs of companies, which are increasingly more diverse and technologically complex. Accredited laboratories are the only ones that guarantee the traceability and reliability of calibration results.

Accredited laboratories cover all areas of calibration (electricity, mechanics, temperature, optical, dimensional, etc.) for a wide variety of variables and equipment, from more "traditional" or "common" – weighing instruments, presses, electrical gauges, etc. to more specific or innovative –video signals, thermometric cameras, exhaust emission analysers and fibre optics– to provide services to all types of industry. .

The "Accredited Bodies” section contains details of all accredited calibration services.

All ENAC documentation relative to accreditation criteria and procedures for calibration laboratories is available in the Documents section.

Legal metrology

State metrological control is applied to measuring equipment or systems that can affect the transparency of commercial transactions, health or consumer and user safety and the environment.

Diverse measuring systems and devices such as those used in the control of basic supplies (water, gas and electricity meters or fuel dispensers), weighing instruments, taximeters, slot machine counters, those used in road safety controls such as vehicle roadworthiness or speed cameras to control vehicle speed or temperature recorders and thermometers used in the transportation, storage and distribution of refrigerated foods, among others, are also subject to this control.

Government agencies, in their respective areas of competence, are responsible for their designation and they use the ENAC accreditation tool as assurance of their technical competence.

In Spain, three are types of conformity assessment body for legal metrology: Notified Bodies, Metrological Control Bodies and Authorised Metrological Verification Bodies.

The first two are concerned with the commercialization and putting into service of the equipment while the latter do so for equipment that is already on the market or for instruments in service.

Placing on the market and putting into service

At this stage, the organisation responsible for product conformity (usually the manufacturer) selects the applicable conformity assessment module/s and instructs a Notified Body or Metrological Control Body to assess the conformity of the measuring instrument with the applicable essential, technical and metrological requirements. At this point, seals to prevent access to certain parts of the measuring instrument are attached to avoid tampering.

Instruments in service

Once the instrument is in operation, it must be checked periodically or after repair or modification to confirm that it reads measurements correctly and that its measurement errors are lower than the maximum permissible errors. If the instrument passes the check, a "conforms” label is attached; if not, a red label is attached disqualifying it for service.

All ENAC documentation relative to accreditation criteria and procedures for Legal Metrology can be found in the Documents section.

Further information:

Examples of accredited calibration services

  • Balances
  • Presses
  • Thermometers
  • Sound level meters
  • Exhaust emission analysers
  • Video signals
  • Fibre Optics
  • Gloss meters
  • Densimeters
  • Gauges and Comparators
  • Transformers
  • Ionisation chambers

State Metrological Control

  • Taximeters
  • Acoustic instruments
  • Electricity meters
  • Pumps or dispensers
  • Weighing instruments
  • Dial gauges
  • Smoke meters
  • Exhaust emission analysers
  • Petrol meters