The Ghana Statistical Service (GSS), in collaboration with the Ministry of Food and Agriculture, has unveiled a landmark series of reports that provide the first nationally representative conversion factors for the countless "non-standard units" (NSUs) used daily in markets and homes across the country.
For decades, a fundamental challenge in producing accurate economic data has been the pervasive reliance on local measurements like the 'olonka', the 'margarine tin', heaps, bundles, and cups. This system, born from traditional commerce, creates significant statistical blind spots because the size of a "margarine tin" or the weight of a "heap" can vary dramatically depending on the region, the commodity, or even the seller.
The new survey provides a scientific basis to translate these familiar but inconsistent units into standard kilogrammes and litres.
The scale of the problem
The Non-Standard Units Survey (NSUS) reveals that these local units are deeply embedded across every part of Ghana's food system. While Ghana adopted the metric system in 1975, the use of NSUs has persisted, creating measurement inconsistencies that distort everything from food prices to national production figures. A seemingly standard unit can represent very different weights. For instance, a medium-sized cup of gari can vary from 0.267 kg in the Bono East Region to 0.292 kg in the Eastern Region.
The variation is even starker at the farmgate. The report found that a "cocoa (jute) sack" of dried yellow maize, a common transaction unit, can weigh anywhere from 131.1 kg in the Greater Accra Region to a staggering 198.0 kg in the Bono East Region—a difference of nearly 67 kilograms.
The survey found that even everyday cooking ingredients are subject to regional variability. For example, a small-sized cup of local rice for household consumption has a national average weight of 0.352 kg, but this can range from 0.320 kg in the Savannah Region to 0.378 kg in the Greater Accra Region. In the market, a medium-sized margarine tin has a national average weight of 0.276 kg but varies from 0.228 kg in the Ahafo Region to 0.346 kg in the Ashanti Region.
The reports also identified some points of consistency. Container-based units for liquids, such as bottles and gallons for selling oil, showed much greater consistency due to their fixed capacities, making them more reliable for measurement.
Policy impact
At a press briefing today, the Government Statistician, Dr. Alhassan Iddrisu, said the development of these conversion factors is a major step forward for Ghana's statistical system.
Dr Iddrisu said by enabling accurate, standardised measurement, the reports will significantly improve the quality of key economic indicators used for policymaking. It will lead to more reliable Gross Domestic Product (GDP) estimates, a more accurate Consumer Price Index (CPI) for tracking inflation, and better data for measuring agricultural production and household consumption.
Establishing a digital repository for these conversion factors and integrating them into all national surveys will help embed this system in the country's data infrastructure. The ultimate goal is to ensure that when a policymaker looks at agricultural output or food inflation, they are seeing an accurate picture—one that reflects Ghana's real economy.