How much firewood do you need at the cabin? Working it out for your season

Most people buy firewood on gut feeling and discover in February that they got it wrong. Here is a simple way to calculate it based on how many weekends you actually spend at the cabin — plus what sacks, cords and cubic metres really mean when you buy.

How much firewood do you need at the cabin? Working it out for your season

Ask ten cabin owners how much firewood they use in a year and you get ten answers that can't be compared. "About a cord." "Twenty sacks or so." "We fill the shed in autumn." None of it tells you how much you need.

The reason is that consumption varies enormously — an insulated cabin with a heat pump for background warmth and the stove for atmosphere, versus an uninsulated cabin where the stove is the only heat source, can differ by a factor of five. But the calculation itself is simple once you break it down.

Start with weekends, not cubic metres

The useful unit isn't cubic metres. It's heat-ups.

Most cabins aren't heated continuously. They sit cold, and then someone arrives on Friday evening and needs to bring the temperature from five degrees to twenty. That warm-up is what costs firewood — keeping a warm cabin warm uses far less.

So the practical starting point is:

Weekends at the cabin during the heating season × wood per weekend = your annual consumption.

Wood per weekend — a starting point

For a weekend from Friday evening to Sunday afternoon, in a cabin that is cold when you arrive:

That corresponds roughly to two to five 60-litre sacks for an ordinary weekend.

If you stay a week during the winter holiday, reckon on roughly double a weekend — the first heat-up is the expensive one, after that it's maintenance burning.

Work out your own number

Line up four figures:

1. Weekends in the heating season. For most people that means October to April — say twelve to twenty weekends, depending on how much you use the cabin.
2. Longer stays. Autumn break, Christmas, winter holiday, Easter. Count each as two or three weekends.
3. Consumption per weekend from the table above.
4. Add 20 per cent. Cold years happen, unexpected visitors happen, and leftover wood doesn't spoil if it's stored properly.

Example: fifteen weekends plus Easter and the winter holiday (another five weekends' worth) = twenty weekends. A moderately insulated cabin at 30 kg per weekend gives 600 kg. Plus 20 per cent: around 720 kg, or a little over three stacked cubic metres.

Sacks, cords or cubic metres — what are you actually buying?

This is where people lose money, because the units don't measure the same thing.

Sacks. Sold in 40, 60 or 1000 litres (bulk bag). A 60-litre sack of dry birch weighs roughly 15–18 kg. A 1000-litre bulk bag is around 250 kg. Note that the litre figure is loose wood with air between the pieces.

Cords and "favn". The Norwegian favn is traditionally 2 × 2 metres and 60 cm deep — that is 2.4 stacked cubic metres. But the word is used loosely in everyday speech, so always ask what the seller actually means.

Cubic metres. And here's the trap: there are two.

• Stacked cubic metre — wood stacked tightly, as it sits in the shed.
• Loose cubic metre — wood tipped loose into a trailer.

Loose wood contains far more air. One stacked cubic metre corresponds to roughly 1.5 loose cubic metres. If you buy "three cubic metres" and get loose measure when you thought you were buying stacked, you receive a third less wood than you expected. This is the most common misunderstanding in firewood sales — settle it before you pay.

Species matters somewhat

The energy is in the mass, not the volume. Heavier species give more heat per cubic metre:

• Birch, beech, oak, ash — heavy hardwoods, most energy per volume, burn steadily and long. The standard at Norwegian cabins.
• Alder and aspen — lighter, burn faster. Excellent for kindling and for autumn and spring burning when you don't need full heat.
• Spruce and pine — light, burn quickly and spit more sparks. Fine for kindling, but you need greater volume for the same heat, and softwood produces more soot if burned too cool.

If you count in kilos, species matters less. If you count in cubic metres, the difference between birch and spruce can be around a third.

How you burn matters just as much

Two cabins with the same wood and the same stove can use very different amounts:

• A clean-burning stove uses wood considerably better than an old one. If your stove predates 1998, you burn more wood for the same heat.
• Choking the air supply to make wood last longer is false economy. Smouldering gives poorer combustion, less heat into the room, more soot in the chimney — and you actually use more wood.
• Dry wood is the single biggest factor. Wet wood can cost you a substantial share of the heat, because the energy goes into boiling off water. We've written about how to store firewood so it actually dries.

Buy for two seasons, not one

The practical advice that solves the most: if you have room, buy a year ahead.

Then you always have one stack that has seasoned for at least a year, and one drying for next season. You stop depending on the supplier having delivered genuinely dry wood, and you avoid panic-buying in February at winter prices.

Firewood is also cheapest in late summer and early autumn, when everyone's shed is full and nobody has started burning yet.

Note what you actually used

After one season of notes you never have to guess again.

Write down how much wood went into the shed in autumn, and how much was left in April. The difference is your real consumption — not an estimate from a table, but the number for your cabin, your stove and your usage. In year two you buy the right amount first time.

If the cabin is shared within the family, this is doubly useful: everyone knows what's left, and who topped it up last.

One place for the things you'd otherwise forget

Digital Hyttebok is built for exactly these notes — firewood use, maintenance, what was done and when, available to everyone who shares the cabin. Next autumn you look it up instead of guessing. It's free to get started.

If you're going through the stove, chimney and the rest before the heating season, the points are in the annual safety check.