LEGAL METROLOGY – THE MEASUREMENTS WE TRUST

Lead

How much fuel we pump, how much electricity we consume, what a scale shows in a shop — all of this must be accurate. Legal metrology is the branch of metrology, and the system, that protects consumers and ensures fair trade, health, and safety.

Main text

In everyday life, we constantly rely on measurements. When we buy groceries and use a scale, when we pump fuel, pay for water or electricity, or when a doctor uses a blood-pressure monitor or a thermometer — we trust that the result is correct. And rightly so: this is not a coincidence, but the consequence of the system of legal metrology.

(Visual 1: Retail scales with visible verification mark / Source: State Office for Metrology)

 

Legal metrology includes regulations, inspections, and accuracy checks of specific measuring instruments used in trade, healthcare, environmental protection, safety, and other fields. In Croatia, responsibility lies with the State Office for Metrology (DZM) and a network of authorised bodies — private companies and public institutions — that regularly inspect scales, meters, fuel pumps, and other instruments.

(Visual 2: Fuel-dispensing pump with visible verification mark / Source: State Office for Metrology)

 

This practice has a long tradition. In Dubrovnik as early as the 15th century, certified measures for wine, oil, and grain were kept in public spaces so that anyone could check a merchant’s honesty. Orlando’s Column bore the engraved length of the Dubrovnik cubit, and city authorities ensured that everyone used the same measures. This was the precursor of today’s legal metrology.

On the international level, legal metrology is coordinated by the OIML (International Organization of Legal Metrology), founded in 1955 — exactly 70 years ago — which issues recommendations and guidelines. In Europe, WELMEC plays an important role in harmonising rules and practices among member states.

(Visual 4: OIML 70th-anniversary logo / Source: Organisation Internationale de Métrologie Légale (OIML))

(Visual 5: Cover page of a WELMEC taximeter guide / Source: WELMEC – European Cooperation in Legal Metrology)

 

For citizens and the economy, this means one thing: measurements are equally accurate and reliable no matter where we are. If we buy a litre of milk in Zagreb or a litre of petrol in Berlin, we can be confident that it is truly the same litre.