Stocks-to-use: the ratio that predicts grain prices
Stocks-to-use is a commodity’s ending inventory divided by the quantity consumed over the same period, expressed as a percentage. It converts a raw tonnage into a measure of cushion: how much of a year’s demand the leftover stock would cover if nothing else arrived.
The conversion is the point. World corn ending stocks of 269.6 million tonnes sound enormous until set against consumption of 1,243.3 million tonnes in the 2026/27 marketing year, which makes them 21.7% of a year’s use, or about eleven weeks (USDA Production, Supply and Distribution). The same tonnage against a much smaller demand would describe a glut.
Why does one ratio move grain prices?
Grain inventory does two different jobs, and the ratio measures the boundary between them. Most of it is pipeline stock: grain in transit, in country elevators, in mill bins, and in the hands of feeders who need a running supply. That portion is not really available, because releasing it would stop the machinery. What sits above the pipeline is buffer, and only the buffer can absorb a bad harvest.
When the ratio is high, a shortfall is met from the buffer and the price barely notices. As the ratio falls toward the pipeline minimum, the buffer thins, and a further shortfall has to be met a different way: by persuading someone to consume less. Feed users switch grains, ethanol plants slow down, importers ration. Price is the instrument that does the persuading, and demand for staple food and feed responds weakly to it. That is what makes the response non-linear. The same one-percentage-point fall in the ratio does almost nothing at 30% and a great deal at 12%.
Two definitional points decide whether a number is comparable. The first is the marketing year, which runs from one harvest to the next and differs by crop and hemisphere; a “2026/27” corn balance is not the same twelve months as a “2026/27” wheat balance. The second is what counts as use. At world level, use means domestic consumption, because one country’s exports are another’s imports and they net out. At country level, use normally means domestic consumption plus exports, which is why a national ratio and a world ratio are built differently.
The numbers themselves come from the US Department of Agriculture’s Production, Supply and Distribution database, revised monthly. They are estimates, and the largest single uncertainty is inventory held inside China, which is substantial and rarely enters world trade.
Six marketing years of world corn balances: production kept rising, but consumption rose faster, and the cushion thinned.
A worked example
Build the corn ratio from its parts. In the 2026/27 marketing year, USDA PSD put world corn production at 1,248.7 million tonnes, domestic consumption at 1,243.3 million tonnes, and ending stocks at 269.6 million tonnes. Dividing stocks by consumption gives 21.7%.
That is the lowest of the six years shown, and the fall was steady rather than dramatic: 27.4% in 2021/22, 27.0% in 2022/23, 26.7% in 2023/24, 24.8% in 2024/25 and 23.8% in 2025/26 (USDA PSD). Note what did not happen. Production did not collapse; it rose from 1,149.2 million tonnes in 2021/22. Consumption simply rose faster, from 1,100.3 million tonnes, and the difference came out of the buffer each year.
Set that beside the price. The World Bank Pink Sheet quoted US No. 2 yellow corn, Gulf export, at $224 per tonne in August 2026, against $185.50 per tonne in August 2025, a rise of 20.8% over twelve months, as the corn price page shows. The correspondence is suggestive, not mechanical: a thinner cushion makes the market more sensitive to news, and more of the news in that window pushed the same way.
Wheat is the useful control. Its world ratio was a comfortable 36.7% in 2026/27, with ending stocks of 259.2 million tonnes against consumption of 707.1 million tonnes (USDA PSD), and yet the Pink Sheet’s US hard red winter benchmark still rose from $231.10 per tonne in August 2025 to $330 per tonne in August 2026, up 42.8%. A high world ratio did not hold the price down, because much of the world’s wheat stock sits where it will not be exported. The wheat and corn pages set out where each crop is grown and traded.
What the ratio does not tell you
It says nothing about location. Grain in a Chinese state reserve and grain in a Gulf export elevator count the same in a world ratio and behave completely differently. Exportable surplus, not total stock, is what an importer bids for.
It says nothing about quality or timing. A ratio measures tonnes at the end of a season; buyers need the right protein, at the right port, in the right month.
And it says nothing about policy. Rice carried a world ratio of 35.7% in 2026/27 (USDA PSD), among the highest of the major grains, while the Pink Sheet’s Thai 5% broken benchmark moved from $356 per tonne in October 2025 to $471 per tonne in August 2026. Restrictions on shipment, of the kind covered under export bans, can tighten a traded market that the world balance sheet calls comfortable. The ratio measures the physical cushion; the spot price measures what a buyer must pay to get at it.
Frequently asked questions
What is the stocks-to-use ratio?
It is the inventory left at the end of a marketing year divided by the quantity consumed during that year, expressed as a percentage. A ratio of 20% means the leftover stock would cover about a fifth of a year's consumption, or roughly ten weeks of supply.
How is stocks-to-use calculated?
Divide ending stocks by total use for the same marketing year and multiply by 100. At world level, use means domestic consumption, because exports from one country are imports into another and cancel out. World corn ending stocks of 269.6 million tonnes against consumption of 1,243.3 million tonnes gives 21.7% for 2026/27 (USDA PSD).
What is a low stocks-to-use ratio?
Low is relative to each crop's own history, not an absolute number. World rice normally carries a much higher ratio than world corn because major producers hold large state reserves. The useful comparison is a crop against its own range over the past decade.
Why does the price response bend upward?
Because comfortable stocks absorb a shortfall and thin stocks cannot. When inventory is ample, a lost harvest is met from the warehouse. When inventory is near the working minimum needed to keep mills running, buyers have to bid consumption away from someone else, and price is the only tool that does it.
Who publishes stocks-to-use data?
The US Department of Agriculture publishes world and country balance sheets in its Production, Supply and Distribution database, updated monthly alongside the WASDE report. Other bodies publish their own estimates, and they differ, mostly because stocks inside China are hard to observe.
Does a low ratio guarantee higher prices?
No. The ratio measures a physical cushion, not a forecast. Wheat carried a comfortable 36.7% world ratio in 2026/27 while the US hard red winter benchmark still rose 42.8% in the twelve months to August 2026 (USDA PSD; World Bank Pink Sheet), because export availability and policy also set prices.
Commodities with a supply-and-demand balance on this site (8)
These are the commodities for which the site carries USDA production, consumption, trade and ending stocks by marketing year, so you can check the ratio yourself.