Grain Drying Costs UK 2026 — Red Diesel vs Gas
With red diesel regularly above 80p/litre and commercial gas prices volatile, grain drying is one of the most significant variable costs in arable farming. A single wet harvest can add £8–15/tonne to your drying bill — knowing your true cost per tonne is essential for accurate enterprise budgeting.
How the calculation works
The calculator uses the standard psychrometric formula to determine water removed per tonne, multiplied by your dryer's thermal efficiency (MJ per kg water evaporated) to give total heat energy required. This is then divided by your fuel's calorific value and multiplied by your current price. Electricity for fans, augers and conveyors is added separately.
Costs are shown both per tonne wet-in and per tonne dry-out. The dry-out figure is the commercially meaningful one — it tells you what drying actually adds to your cost of production.
Dryer efficiency benchmarks
AHDB and Farm Energy Centre data suggest continuous flow tower dryers achieve around 3.5 MJ/kg water, mixed flow dryers ~4.0 MJ/kg, and batch recirculating dryers ~4.5 MJ/kg. An old or poorly maintained batch dryer can be as poor as 5.5 MJ/kg — nearly 60% more fuel per tonne than a modern continuous flow system.
Frequently Asked Questions
- How much does it cost to dry wheat per tonne in the UK?
- At ~85p/litre red diesel drying wheat from 20% to 14.5% in a standard batch dryer costs around £7–9/tonne. A continuous flow dryer at the same price cuts this to £5–7/tonne.
- How much red diesel does a grain dryer use per tonne?
- A batch recirculating dryer uses approximately 10–14 litres per tonne to dry from 20% to 14.5%. A continuous flow dryer uses roughly 7–10 litres for the same job.
- Is gas or red diesel cheaper for grain drying?
- It depends entirely on current prices. Gas generally has a lower cost per MJ of energy when prices are normal, but dryer capital costs differ. Enter your current prices above to compare directly.
- What is grain shrinkage when drying?
- Drying wheat from 20% to 14.5% reduces the weight by approximately 64 kg per tonne — around 6.4%. You get fewer tonnes out than you put in, which must be accounted for in yield and value calculations.