How Many Stères of Firewood Do You Need for Winter?

When the temperatures drop, plenty of people rush to buy firewood - yet very few are confident about how much they’ll actually get through.

Working out your firewood supply has become a real pressure point for anyone who relies on a wood-burning stove or a fireplace insert. Get the maths wrong and you might be scraping by in January; overbuy and you’re left with a pile of timber sitting in the garden, tying up both space and money. The key question is straightforward: how many stères do you need to get through a winter without any nasty surprises?

What a stère of firewood really means

From a seller’s point of view, it can sound self-explanatory. In reality, a lot of confusion starts with the unit itself. The stère comes from French usage and, in principle, equals one cubic metre of stacked logs when the logs are 1 metre long.

In day-to-day buying, though, the calculation shifts depending on how long the pieces are.

"A stère is one cubic metre of stacked firewood, but the real volume of wood changes depending on the length and shape of the logs."

When logs are cut to 50 cm, 40 cm or 30 cm to fit a stove or an insert, the stack becomes tighter, with fewer air gaps between pieces. The result is that the same “stère” can contain more actual wood, even though the apparent stacked volume looks smaller.

That’s where many buyers get caught out: they order “5 stères” without knowing whether the supplier is talking about 1 m logs or shorter lengths. This difference affects the price, the true quantity of firewood delivered, and how much storage space you’ll need.

Why this changes your winter calculations

If you only compare the number of stères, it may feel as if you’re paying more - or receiving less - than someone else. In practice, what matters is the mass of wood and its heat output, not just the apparent stacked volume.

On larger orders, a 10% to 20% swing in the real amount of wood per stère can translate into several extra weeks of heating - or several weeks less.

The biggest factors that decide how much firewood you’ll need

There isn’t one magic number of stères that fits everyone. Consumption depends on a mix of variables which, taken together, determine whether your home is a “heat-hungry” one or relatively economical to warm.

Floor area and internal volume

Two homes of 100 m² can have completely different heating needs. A compact single-storey property with standard ceiling height will usually need far less firewood than an older building with high ceilings and long corridors.

Broadly speaking, the greater the internal volume (the cubic metres of air you must heat), the bigger the firewood stack you’ll need to face winter comfortably.

Thermal insulation: walls, windows and roof

Well-insulated homes - with double glazing and particular attention to the roof and external walls - can cut firewood use by 30% to 50% compared with older, draughty properties.

"In practice, every investment in insulation directly reduces the number of stères needed per winter."

People living in older homes often notice the difference immediately: logs disappear quickly, rooms take longer to warm up, and the temperature drops again soon after.

Appliance type: stove, insert or open fireplace

Your appliance’s efficiency is another major dividing line. Modern wood-burning stoves and closed inserts commonly achieve 75% to 80% efficiency, using most of the energy stored in the wood.

By contrast, open fireplaces can waste up to 70% of the heat straight up the chimney. In that situation, the comfort is often more about seeing the flames than about properly heating the house.

Wood species: hardwood or resinous softwood

Not all firewood produces the same heat. In general, woods fall into two groups:

• Hardwoods (such as oak, beech, and other dense native species): burn more slowly, release heat steadily, and create long-lasting embers.
• Resinous softwoods (pine, young eucalyptus, conifers in general): ignite quickly and give a strong burst of heat, but for a shorter time, so you have to refuel more often.

For an entire winter, many people choose a blend: hardwoods to form the base of the firebed, plus a few resinous pieces to relight easily and raise the temperature quickly.

Local climate and how you use the fire

A harsh winter with many sub-zero days calls for near-continuous burning. Milder areas allow long spells with the appliance off during the day. Daily running hours can matter just as much as the quality of the logs.

How many stères you need depending on how you heat

Drawing on the experience of firewood users and wood-heating technicians, some typical consumption bands can help with planning.

Type of use	Usage profile	Average consumption per winter
Occasional	Weekends, occasional evenings	1 to 3 stères
Regular support	Supplementing central heating on cold days	3 to 6 stères
Main source	Firewood provides most of the home’s heating	5 to 12 stères

Occasional use: firewood for enjoyment, not necessity

If you only light the fire on a handful of cold days - or mainly to create atmosphere when friends are round - 1 to 3 stères is usually enough. Here, the bigger risk is buying far more than you’ll use and leaving logs sitting for years.

Support heating: sharing the load with another system

In homes with electric, gas or oil heating, a wood-burning stove is often used to soften the energy bill and boost comfort on particular days. Households that run the stove on most cold evenings typically get through 3 to 6 stères per season.

Main heating source: when firewood is the priority

If you depend on firewood for most of your heat, typical usage ranges from 5 to 12 stères each winter. A well-insulated home with an efficient appliance may stay comfortable near the lower end. Large, older and colder houses can push towards - or even beyond - the upper end.

"Before placing the order with the supplier, it’s worth running a quick simulation: floor area, insulation quality, appliance output, and how much time the family spends at home."

Adjustments that can shrink your firewood stack

Seasoning and wood quality

Wet firewood is a clear enemy of domestic heating. Moisture above 20% reduces the heat you get, creates lots of smoke, encourages creosote build-up in the chimney, and increases the risk of a flue fire.

• Choose logs that were cut at least one year in advance.
• Avoid very green pieces or wood with a strong sap smell.
• If possible, use a moisture meter to check your stock.

Maintenance of the stove or insert

A dirty appliance loses efficiency. Too much ash, residue on the glass, and greasy deposits in the flue can all cause poor combustion. The chimney should be professionally swept at least once a year, and insurers often require this.

Incremental insulation improvements

A full renovation isn’t always realistic. Even so, small steps - sealing draughts, adding heavier thermal curtains, and improving loft insulation - can reduce how often you need a strong, roaring fire.

Storage: where and how to keep several stères

Having enough firewood is only half the job; it also needs to be stored properly. Ideally, keep it in a ventilated spot, sheltered from direct rain and not in contact with the ground.

• Use bearers, slats or pallets to lift the wood off the floor.
• Cover the top with a tarp or a simple roof, but leave the sides open so air can circulate.
• Don’t stack the pile against the house wall, to avoid damp and pests.

"Good storage turns firewood bought today into a better fuel a few months from now, with lower moisture and higher performance."

Practical simulations to avoid buying the wrong amount

Picture a 90 m² home that’s reasonably well insulated, in a moderate-winter area, with a modern insert and nightly use. Typical consumption sits at around 4 to 5 stères. If that same house were in a mountainous region with more severe cold and near-continuous use, the figure could climb to 7 or 8 stères.

Now consider an older 140 m² house with poor insulation, heated mostly by firewood, using a closed fireplace with average efficiency. The household can easily burn through 8 to 10 stères, especially if they spend many hours at home - for example, when working from home.

Terms worth knowing

Two ideas come up again and again:

• Calorific value: the amount of energy released when a given mass of wood is burned. Denser woods generally offer a higher calorific value per unit volume.
• Appliance efficiency: the percentage of the wood’s energy that becomes useful heat inside the home. The higher this number, the fewer stères you’ll need.

Understanding these concepts helps you negotiate with suppliers, compare offers and - most importantly - set realistic expectations: sometimes it’s worth paying a bit more for better-quality logs and burning less over the winter.

If you’re new to using a wood-burning stove or insert, a cautious approach is to buy slightly above your initial estimate in the first year, track what you actually use month by month, and then adjust the quantity for the following seasons. This kind of “real-world calibration” usually prevents shocks - both when the cold arrives and when you check your bank balance.