Findings from Ghana’s first nationally representative Non-Standard Units Survey (NSUS) have revealed significant variations in the quantities represented by commonly used local measurement units across households, markets and farmgates, highlighting longstanding challenges in producing accurate agricultural and economic statistics.
The survey, conducted by the Ghana Statistical Service (GSS) in collaboration with the Ministry of Food and Agriculture (MoFA), found that identical local units, including cups, sacks, margarine tins, bundles, heaps and size classifications, often represent different weights depending on the commodity and region. The findings reinforce the need for “scientifically derived conversion factors” to improve the accuracy of official statistics used in policymaking, food security assessments, inflation measurement and national accounts.
At the household level, the survey established that food consumed using seemingly identical measuring containers differs considerably across the country. A small cup of local rice records a national average weight of 0.352 kilogram, while a medium-sized cup averages 0.491 kilogram. However, regional disparities remain pronounced, with a small cup of local rice weighing 0.320 kilogram in the Savannah Region compared with 0.378 kilogram in the Greater Accra Region.
Similar differences were observed across other staple foods. A small-sized Puna yam weighs an average of 1.043 kilograms nationally, but reaches 1.564 kilograms in the Bono Region. Likewise, the average weight of a medium-sized cup of gari ranges from 0.267 kilogram in Bono East to 0.292 kilogram in the Eastern Region, demonstrating that even familiar household measures cannot be assumed to represent uniform quantities across the nation.
The broader household analysis also revealed comparable inconsistencies in commodities such as corn flour, soybeans, avocados, and coconuts, indicating that “standard-looking units” frequently conceal substantial differences in actual weight across regions.
At the farmgate, the survey found even greater disparities in the quantities represented by common trading units used by farmers.
Among dried yellow maize producers, the cocoa or jute sack remains the dominant transaction unit in only seven regions. Yet the average weight of the same sack ranges from 131.1 kilograms in the Greater Accra Region to 198.0 kilograms in the Bono East Region, a variation of nearly 67 kilograms.
The report further showed that size-based classifications such as small, medium and large are unreliable indicators of actual weight. While 100 large yam tubers weigh an average of 362.7 kilograms nationally, regional differences persist, with the Northern Region recording the highest average.
Additional farmgate findings revealed significant variations in produce sold using buckets. A blue rubber bucket of local tomatoes records a national average conversion factor of 3.827 kilograms but ranges from 3.496 kilograms in the Volta Region to 4.122 kilograms in the North East Region. Similarly, white paint buckets used for fresh okro vary considerably across size categories and regions, reflecting differences in “filling practices” and produce aggregation methods.
In contrast, the survey found that container-based measurements for liquid commodities, particularly oils sold in bottles and gallons, display relatively greater consistency because of their fixed capacities.
The market survey reached similar conclusions, showing that widely accepted retail measures often represent different quantities depending on location.
A medium-sized margarine tin, for instance, has a national average weight of 0.276 kilogram but ranges from 0.228 kilogram in the Ahafo Region to 0.346 kilogram in the Ashanti Region.
Regional differences were equally evident in yam trading. Medium-sized yams weigh an average of 1.772 kilograms nationally, with weights ranging from 1.301 kilograms in the Ashanti Region to 2.042 kilograms in the Volta Region.
Beyond these examples, the market analysis found notable variations in commodities traded using olonka tins, bundles, heaps and single-unit classifications. White maize sold in olonka tins differs significantly across regions, while cabbage and cocoyam leaves sold by size or bundle also display considerable variation. Palm oil packaged in water bottles, however, emerged as one of the more consistent measurement practices, highlighting the relative reliability of fixed-capacity containers compared with loose or size-based units.
Taken together, the findings establish what GSS describes as the country’s first “nationally representative evidence” for converting non-standard units into kilograms and litres, providing an empirical basis for harmonising agricultural measurements across Ghana.
The findings provide a strong case for establishing and institutionalising nationally recognised conversion factors for non-standard units across Ghana. A harmonised measurement framework would help standardise transactions from farmgate to market and household level, promote fairness in trade by reducing inconsistencies in quantities exchanged, minimise the risk of buyers and sellers being disadvantaged, and provide policymakers with more accurate and comparable data for agricultural planning, inflation measurement, food security monitoring and broader economic decision-making.
