How much heating oil to order

Start with how much room is in your tank, not with the price. Check the gauge, then use the Tankful tank planner to estimate the space. Ask the supplier to confirm a safe fill, because gauges are approximate and a tank should never be filled to the brim.

Most oil suppliers price by the litre and charge less per litre for bigger orders. In Great Britain many suppliers start at 500 litres. In Northern Ireland smaller orders are common and many suppliers publish prices for 300, 500 and 900 litres, but the price per litre is usually higher for smaller amounts.

Compare the same quantity. A 900 litre price and a 500 litre price are not comparable until you divide each total by the litres. Ask whether a small-order charge applies and whether delivery is included.

Ordering a larger amount less often usually costs less overall, if your tank has the room and you can afford the bill. If the budget is tight, a smaller top-up is better than running out, which can mean an emergency delivery and a boiler restart.