How much does a wood-burning fireplace use per month? Real consumption and cost calculation

It is the question we hear most from customers who are thinking about installing a fireplace or moving from using it “some weekends” to heating the house with it every day: how much will it really cost? The honest answer is that it depends far more on the type of firewood and how you light the fire than on the size of the fireplace, and almost nobody takes the second factor into account.

How much firewood is actually burned on a winter day

A medium-sized fireplace or insert, lit for around 5–6 hours a day during a typical winter in Catalonia, uses between 15 and 25 kg of firewood per day. The range is so wide because it depends on whether you use hardwoods (holm oak, oak), which provide more heat per kilogram, or softwoods (pine), which burn much faster for the same amount of heat.

The calculation, with real figures

If you buy already seasoned holm oak or oak firewood, the price is usually between €0.20 and €0.35 per kilogram depending on the area and whether you buy it in small bags or by the truckload (buying a large quantity by truck is always considerably cheaper per kilogram). With consumption of 20 kg per day over around 25–28 days of actual use per month in peak season, monthly spending on firewood is roughly €100–€190. If you use pine or other softwoods, the price per kilogram is usually lower, but you need to burn more to produce the same heat, so the real saving is smaller than it first appears.

What nobody tells you: the hidden cost of poorly seasoned firewood

Damp firewood does not only produce more smoke and creosote — it also performs worse. Much of the energy from combustion is used to evaporate the water contained in the wood instead of heating the room. Burning wood with more than 25–30% moisture can mean you need 20–30% more firewood to obtain the same heat as properly seasoned wood below 20% moisture. It is literally money going up the chimney.

How to reduce spending without sacrificing heat

• Buy your firewood a year in advance and store it in a well-ventilated place — buying it “for immediate use” is almost always more expensive and sometimes it is not as dry as promised.
• Combine hardwoods (to maintain embers) with softwoods (for lighting), instead of using only one type.
• Check the condition of the flue: a dirty or partially obstructed flue reduces performance and means you need more firewood for the same amount of heat.
• If your fireplace is a traditional open fireplace, consider installing an insert: the real thermal efficiency of an open fireplace is usually around 15–20%, compared with 70–80% for a modern closed insert. The difference in firewood consumption for the same amount of heat is significant.

Frequently asked questions