The Ghana Statistical Service (GSS) has introduced a national conversion system to translate commonly used informal measurement units such as olonka, margarine tins, cups, heaps, bundles and sacks into standard weights, in a move aimed at improving the accuracy of agricultural and food statistics.
The initiative, known as the Non-Standard Units Survey (NSUS) 2026, provides Ghana’s first nationally representative conversion factors for local measurement systems used across households, markets and farmgate transactions.
For decades, agricultural commodities in Ghana have largely been bought and sold using traditional measures that are familiar to traders, farmers and households. However, the actual quantity represented by these measures often differs depending on the commodity, location and transaction point.
The Ghana Statistical Service (GSS) said the widespread use of these units has created challenges in producing consistent and comparable statistics for agriculture, food consumption and market analysis.
“Across Ghana, these non-standard units remain the dominant way agricultural commodities are measured, traded and consumed. However, because the same unit often represents different quantities across commodities and regions, producing consistent and comparable agricultural statistics has long been a challenge,” the GSS said.
The survey covered three key areas of Ghana’s food system, households, markets and farmgates, where commonly used units were identified, weighed and analysed to establish conversion factors.
The conversion factors will allow measurements such as cups, tins, sacks and bundles to be converted into standard units such as kilograms and litres, improving the reliability of official data.
The GSS said the findings will strengthen the measurement of agricultural production, food consumption, food security and major economic indicators.
“By establishing scientifically derived conversion factors, the NSUS provides a stronger foundation for measuring production, trade, consumption, food security, and major economic indicators such as the Gross Domestic Product (GDP) and Consumer Price Index (CPI), ultimately improving the quality of evidence that informs agricultural policy and national development,” the Service said.
One of the major findings from the survey was the significant variation in the weight of commodities sold using similar local units.
At the farmgate level, dried maize sold in cocoa (jute) sacks recorded average weights ranging from 131.1 kilograms in the Greater Accra Region to 198 kilograms in the Bono East Region, a difference of nearly 67 kilograms despite traders using the same type of measurement.
The survey also found differences in household measurements. A small cup of local rice weighed an average of 0.352 kilograms nationally, but varied from 0.320 kilograms in the Savannah Region to 0.378 kilograms in the Greater Accra Region.
Similar variations were recorded in market measurements. A medium-sized margarine tin, commonly used by traders, had a national average weight of 0.276 kilograms, but ranged from 0.228 kilograms in the Ahafo Region to 0.346 kilograms in the Ashanti Region.
The findings highlight the challenge of relying on traditional measurement systems without accurate conversion factors, particularly when comparing food prices, estimating agricultural output or assessing household consumption.
The survey found that some local measurement methods are more consistent than others. Container-based units, especially bottles and gallons used for liquids such as palm oil, showed relatively greater consistency because they have fixed capacities.
However, loose measurement methods such as heaps, bundles and size classifications including “small”, “medium” and “large” showed wider variations across regions.
For example, medium-sized yams sold in markets recorded a national average weight of 1.772 kilograms, but ranged from 1.301 kilograms in the Ashanti Region to 2.042 kilograms in the Volta Region.
The GSS said the conversion factors developed through NSUS will support improvements in the compilation of the Consumer Price Index (CPI), agricultural statistics, household consumption surveys and national accounts estimates.
The Service also plans to establish a digital repository containing conversion factors and photographs of commonly used local measurement units to support future statistical exercises.
The introduction of NSUS marks a significant step towards aligning Ghana’s everyday trading practices with official statistical measurement systems, ensuring that transactions conducted through traditional units can be accurately reflected in national economic data.
