Measure the pile or enter the volume you were quoted, pick how the wood is stacked and which species it is, and the tool works out the solid wood inside it, the mass, the heat in kilowatt-hours and — if you add a price — what that heat costs per kWh. It is the only fair way to compare a cheap load of poplar with an expensive one of hornbeam.
Usually the log length — 0.33 m, 0.5 m or 1 m.
Loose wood tipped off a truck holds far less than stacked.
To get the cost per solid m³ and per kWh.
Enter the pile dimensions or the quoted volume.
How it works
A stacked cubic metre is mostly wood and partly air. Stacked split logs are roughly 70% wood, stacked round logs about 80% because they lie closer, and wood tipped loose off a truck only about 50%. Multiplying the volume you paid for by that fraction gives the solid wood you actually received.
Solid volume times the species density gives the mass, and air-dry wood yields about 4 kWh per kilogram regardless of species. That is the key insight: a kilogram of poplar and a kilogram of beech hold nearly the same energy, but a cubic metre of beech holds far more kilograms. So beech is not better wood per kilo — it is denser, and you buy by volume.
Moisture decides how much of that heat you actually get. The figures here assume air-dry wood at roughly 20% moisture, the state seasoned firewood reaches after a summer stacked under cover with open sides. Freshly cut wood at 50% moisture delivers roughly a third less usable heat per kilogram, because the fire spends energy boiling water out of the logs, and it tars up the flue while doing it.
Practical examples
One stacked cubic metre of beech
Split and stacked, that is 0.7 m³ of solid wood, about 511 kg and roughly 2,044 kWh of heat — the energy in about 204 litres of heating oil.
A pile 4 m long, 1.5 m high, 1 m deep
6 stacked m³ of split beech is 4.2 m³ solid, about 3,066 kg and 12,264 kWh. Measuring the delivered pile before it is moved is the only check you get.
Why species matters more than price per cubic metre
One stacked m³ of poplar gives about 1,260 kWh against 2,044 kWh for beech — 38% less heat from the same volume. Cheap poplar has to be nearly 40% cheaper to break even.
Comparing two offers
Beech at 9,000 per stacked m³ works out at about 4.40 per kWh; spruce at the same price costs about 6.84 per kWh, because a cubic metre of spruce holds far fewer kilograms.
Frequently asked questions
What is the difference between a stacked and a solid cubic metre?
A stacked cubic metre ("prostorni metar") is a metre-cube of space filled with stacked logs, gaps included. A solid cubic metre is the wood itself. Split logs stacked neatly contain roughly 0.7 m³ of wood per stacked m³.
And a loose cubic metre?
Wood tipped off a truck without stacking holds only about half its volume as wood. If a load is quoted loose, expect roughly 30% less wood than the same figure stacked — the single most common misunderstanding in a firewood sale.
How much does a cubic metre of firewood weigh?
For air-dry beech, about 511 kg per stacked m³ or 730 kg per solid m³. Fresh-cut wood of the same species weighs far more because up to half its mass is water.
Is beech really better than spruce?
Per kilogram they are nearly identical — about 4 kWh either way. Beech simply packs more kilograms into the same space, so it wins when you buy by volume and lose interest in reloading the stove.
How much heat do I lose burning wet wood?
Roughly a third at 50% moisture compared with air-dry. Some of the energy goes into evaporating water instead of heating the room, and the cooler flue gases deposit tar and creosote in the chimney.
How long does firewood need to season?
Typically one to two years for hardwoods, split and stacked off the ground with the sides open and the top covered. Species, length and climate all matter; a moisture meter on a freshly split face is worth more than a calendar.
Does the tool include stove efficiency?
No. It gives the energy in the wood. A modern stove delivers perhaps 75–80% of that into the room, an old open fireplace far less, so divide accordingly when sizing a winter supply.
How does the heating-oil comparison work?
One litre of heating oil holds about 10 kWh, so the tool divides the wood energy by ten. It is a like-for-like energy comparison only; it ignores appliance efficiency and the price of each fuel.
Why compare offers by cost per kWh?
Because that is the price of the heat you actually buy. Two loads at the same price per cubic metre can differ by 40% in delivered energy once species and stacking are accounted for.
How do I measure a delivered pile?
Stack it, then measure length, height and depth in metres and multiply. Measure before you burn any: a pile is easiest to dispute while it is still where the truck left it.
Are the densities exact for my wood?
No — they are typical values for air-dry wood. Density varies with growth site and within a load, and bark and knots shift it further. Expect the result to be right within a few percent, not to the kilogram.
Is anything uploaded?
No. The calculation runs in your browser and nothing about your purchase is sent anywhere.
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