In Italian metrology, «taratura» and «calibrazione» are often used as if they meant the same thing. They do not. If your organisation works with Italian suppliers, receives certificates from an Italian accredited laboratory, or manages instruments across sites that include Italy, this distinction is not a linguistic curiosity: it can decide whether a document satisfies an ISO 9001 or ISO/IEC 17025 audit.
What the VIM actually says
The reference for these terms is the VIM (International Vocabulary of Metrology), adopted in Italy as the UNI CEI 70099 standard. The VIM defines «taratura» as the operation that, under specified conditions, establishes a relationship between the values shown by a measuring instrument and the corresponding values provided by traceable measurement standards, for example a certified reference resistor used as a standard for resistance measurements. This is a passive operation: it observes and documents any deviation, it does not touch the instrument itself. The result is recorded in a taratura report or certificate, which may include a statement, a correction curve, or a table of deviations.
For the operation that actually acts on the instrument, bringing it back to give correct readings, the VIM uses a different term: adjustment. This is where the Italian confusion begins. The VIM explicitly notes that the word «calibrazione» should not be used to mean «taratura», since it is misleading: it comes from an imprecise translation of the English word «calibration», which in fact corresponds exactly to the Italian «taratura». In everyday Italian industrial usage, however, «calibrazione» has become the practical synonym for «regolazione» (adjustment), and that is the sense in which we use it in this article, to stay close to the language actually spoken on the shop floor.
Taratura vs calibrazione: the practical difference
| Taratura | Calibrazione (adjustment) | |
|---|---|---|
| What it does | Compares the instrument against a traceable standard | Corrects or adjusts the instrument |
| Does it change the instrument? | No | Yes |
| Output | Taratura certificate or report | Instrument adjusted, within tolerance |
| Typically performed by | An ISO/IEC 17025 accredited laboratory (in Italy, a LAT centre) | A laboratory technician or the manufacturer's service |
| Purpose | Traceability, audits, metrological traceability | Correct instrument performance in the field |
In practice: the instrument is checked against a standard first (taratura), then, only if needed, adjusted (calibrazione). The check tells you whether the instrument is still reliable; the adjustment only comes into play if the deviation found is larger than the tolerance acceptable for the intended use.
Why confusing the two terms is a real risk
This is not a footnote in a metrology handbook. If a quality manager asks for «una calibrazione» when the management system procedure (ISO 9001, or a Defense or Aerospace specification) actually requires a certified, traceable «taratura», the result can be an instrument that is technically more accurate, yet without the documentation needed to pass an audit. In sectors where metrological traceability is a contractual requirement, such as electronic board testing, validation of Defense systems, and Aerospace test benches, the taratura certificate is not an accessory: it is the proof that the measurement is reliable and traceable to national or international standards.
What an ISO/IEC 17025 accredited laboratory guarantees
ISO/IEC 17025 sets out the technical competence and impartiality requirements for testing and calibration laboratories. In Italy, laboratories accredited for this activity are commonly known as LAT (Laboratori Accreditati di Taratura, meaning accredited calibration laboratories). A certificate issued by an accredited laboratory guarantees:
- metrological traceability of the measurement to national or international standards;
- calculation of measurement uncertainty, the element that distinguishes a professional taratura from a simple internal check;
- international recognition of the certificate, through the ILAC MRA mutual recognition arrangements.
How often should an instrument undergo taratura?
There is no universal interval that applies to every instrument. The correct periodicity depends on the type of instrument, how intensively it is used, the manufacturer's specifications, and the requirements of the company's quality management system. For this reason, good practice, especially for large instrument fleets in industrial, research, Defense, or Aerospace settings, is to maintain a taratura plan that tracks the due date for each individual instrument, rather than applying one fixed rule to all of them.
ALLdata's role
For more than 45 years, ALLdata has supported laboratories, production departments, and research centres in managing measuring instruments: from selecting the right instrument, such as the Transmille multifunction calibrators used to check multimeters and other instruments, to planning the taratura and calibrazione activities needed to keep it reliable over time. This is an essential piece for anyone operating in sectors where metrological traceability is a requirement, not an option.
Do you have an instrument fleet to organise, or do you need to understand which taratura interval makes sense for your application? Talk to an ALLdata engineer, or take a look at our metrology and calibration solutions.