Grain Drying Cost & What It Costs To Dry

Drying cost = energy to evaporate the water × the price of that energy. First the water to remove is found from the wet mass and the starting and target moisture, then it's multiplied by a specific drying energy (the heat needed per kilogram of water, including dryer losses), giving total energy. Dividing by the fuel's energy content gives the fuel quantity, and multiplying by the fuel price gives the cost.

Water removed = mass × (Mi − Mf) ÷ (100 − Mf), where Mi is the initial moisture percent and Mf the final. Drying 10 tonnes of paddy from 22% to 14% removes 10,000 × (22 − 14) ÷ (100 − 14) ≈ 930 kg of water. The formula keeps the dry matter constant and only the water changes, which is why the divisor uses the final moisture.

It's the heat needed to evaporate one kilogram of water from the grain. The pure latent heat of water is about 2.3 MJ/kg, but real dryers waste heat in exhaust, walls and heating the grain, so the practical figure is around 3–6 MJ per kg of water. This tool defaults to 4.5 MJ/kg; efficient continuous dryers sit lower, simple batch and bin dryers higher.

The tool uses diesel 38.6 MJ/L, LPG 46 MJ/kg, electricity 3.6 MJ/kWh, firewood ~15 MJ/kg and biomass ~14 MJ/kg. Dividing total drying energy by the fuel's energy content gives the litres, kilograms or kWh required, which is then priced. Wood and biomass figures assume air-dry fuel; wet fuel delivers far less usable heat.

Drying below the safe storage moisture burns fuel you didn't need to burn, and it also removes saleable weight — grain is usually sold by weight, so every extra point of moisture taken out is product you no longer get paid for. The tool shows the dried weight and weight-loss percent so you can see both the fuel and the lost-tonnage cost of going too far.

It depends on the grain and how long you'll store it. Common safe targets are around 13–14% for paddy and wheat and 13% for maize for medium-term storage, lower for long-term or for oilseeds. Drying to the recommended target — and no further — protects against mould and insects without throwing away weight or fuel.

Cost per tonne is the total drying cost divided by the tonnes dried, giving a like-for-like figure to compare fuels, dryers and seasons. A wetter intake or a lower target moisture pushes it up; a more efficient dryer or cheaper fuel pulls it down. It's the number to track when deciding whether on-farm drying beats paying a commercial dryer.

Yes — pick from eight currencies and enter the fuel price in your own money. The energy and water figures are physical and currency-independent; only the final cost and cost-per-tonne are converted, so you get results that make sense whether you buy diesel by the litre, LPG by the kilo or electricity by the unit.

They're solid planning estimates. Real costs vary with dryer efficiency, ambient humidity, airflow, how the fuel is burned and the moisture meter's accuracy. Treat the result as a budget and benchmark: measure your actual fuel use over a batch, compare it to the estimate, and refine the specific-energy figure to match your own dryer.

Yes — run the same grain and moisture targets, then switch the fuel and price to see how diesel, LPG, electricity, firewood and biomass stack up per tonne. Because the water and energy needed stay the same, the comparison comes down to each fuel's energy content, price and how cleanly your dryer burns it.