How Much Coal or Firewood Should I Buy? How Long Does 1 Tonne of Coal Last?

Short answer: how many months a tonne of coal lasts depends on how many kilograms your stove burns a day. A stove burning 10 kg a day gets through 1 tonne in about 3 months (14 weeks); one burning 20 kg a day in about 1.5 months (7 weeks). The sum is 1,000 kg ÷ daily kg.

Current prices and types: Coal prices →

Single-number answers to “how many tonnes does a 100 m² house burn?” are guesses. Instead of unsourced ranges, this article gives you the arithmetic that is certain and a way to measure your own consumption. For a ready-made estimate for your home you can also use our fuel needs calculator.

How many months does 1 tonne of coal last?

A tonne is 1,000 kg. If you know how many kilograms your stove burns a day, divide 1,000 by it; divide the result by 7 for weeks and by about 30.4 for months. The table below is just that division, and the same sum works for coal and for firewood. Our heating coals come in 25 kg bags, so we added the number of bags per week.

The table answers two more questions. “How many tonnes of coal a month?” A stove burning 10 kg a day uses about 300 kg a month, and one burning 20 kg a day about 600 kg; a full tonne a month needs about 33 kg a day. “How long does a tonne of firewood last?” The sum is the same: at 20 kg of wood a day, a tonne lasts about 7 weeks. Measure daily kilos of wood the same way, by counting sacks.

How do I measure my own consumption?

The most reliable figure is your own. In the first weeks of the season, write down the date each time you open a bag. If a 25 kg bag lasts half a week, you burn 2 bags, or 50 kg, a week, which is about 7 kg a day. Multiply by the number of weeks your season usually lasts and leave a margin for the coldest weeks. Burn times per load are covered in how long stove coal burns.

How many tonnes of coal does a flat burn?

There is no single answer for everyone. We removed the tonne and stere ranges this article used to give because we could not confirm them from a reliable source. Heated area, insulation, ceiling height, stove efficiency and climate decide consumption together. The practical route: measure your daily use in the first weeks and multiply by the length of the season. For example, an average of 10 kg a day over a 20-week season is 10 × 7 × 20 = 1,400 kg, or about 1.4 tonnes.

If I switch from lignite to imported coal, how many tonnes do I need?

The tonnes needed for the same heat are inversely proportional to calorific value. Compare the values stated on the two bags on the same basis and divide. Example: according to the bag statements, boiler coal at 7,400 kcal/kg as received and Soma coal with a net calorific value of 4,800–5,200 kcal/kg (midpoint 5,000): 7,400 ÷ 5,000 ≈ 1.5. So you need roughly 1.5 times as much Soma coal for the same heat. A dry-basis value is higher than the real heat of moist coal, so do not divide a dry-basis figure by an as-received one. Stove efficiency also shifts the result. How to read the values on a bag is explained in the values on a coal bag.

How many tonnes is 4 steres of wood, and how much space does a tonne take?

A stere is a 1 m × 1 m × 1 m stack of firewood. Türkiye’s General Directorate of Forestry (OGM) assumes an average stere weighs 500 kg. On that basis 4 steres are about 2 tonnes and 6 steres about 3 tonnes, and 1 tonne of wood is about 2 steres, roughly 2 m³ of neat stack. The same OGM publication stresses this is an average: its study of Scots pine in Eastern Anatolia found an air-dry stere weighed around 266 kg. Species, piece thickness and moisture change the figure a lot. See how many bags and steres in a tonne of firewood.

Is winter shorter in the Aegean?

Many consumption tables online are written for cold regions. Long-term data from the Turkish State Meteorological Service give a January mean of 8.9 °C at the İzmir station and -9.1 °C at Erzurum. That gap shows why applying tonnage written for a cold province to the Aegean can mislead. But the İzmir station is one point; winters are harsher at higher altitude. Your own measurement is still the best guide.

What does it depend on?

• Heated area: the rooms you actually heat, not the whole house.
• Insulation and draughts: single glazing, gaps under doors and roof losses raise consumption.
• Ceiling height: a larger heated volume needs more fuel.
• Calorific value and moisture: you burn more kilos of low-calorie or wet fuel.
• Stove and use: stove efficiency, air setting and hours of use per day.
• Climate and altitude: how long and how hard the winter is.

What should I watch for when burning?

No fuel is smokeless; every coal or wood stove can produce carbon monoxide. The TKİ (Turkish Coal Enterprises) guide recommends top-down lighting, not adding coal afterwards, and keeping the lower air inlet and flue damper open at night; if poisoning is suspected, ventilate and call 112. The Ministry of Health describes carbon monoxide as colourless, odourless and poisonous. For symptoms and choosing a detector, read carbon monoxide detectors and stove gas symptoms.

Should I buy all at once or in parts?

Buying in bulk needs dry, covered storage raised off the ground. If space is tight, buy part of your need at the start of the season and top up based on the consumption you measure; that also gives a more accurate estimate. For prices see the current price list, and for bag vs tonne pricing our article how much is a tonne of coal.

Frequently asked questions

How many months does 1 tonne of coal last?

About 3 months at 10 kg a day, about 2 months at 15 kg a day and about 1.5 months at 20 kg a day.

How many kg is a bag of coal?

Our heating coals come in 25 kg bags and our coke-type coal in 40 kg sacks; a tonne is 40 bags of 25 kg. More in how many kg in a bag of coal.

How many tonnes is 6 steres of wood?

About 3 tonnes on OGM’s assumption of 500 kg per stere; light, thin wood can weigh noticeably less.

How many tonnes of coal are burned in a month?

Usually less than a tonne: about 300 kg a month at 10 kg a day, about 600 kg at 20 kg a day.

Does the calculator give an exact result?

No, it gives an estimate. Compare the calculator result with the consumption you measure in the first weeks.

Sources: General Directorate of Forestry (OGM), “Stere conversion factors of Scots pine firewood in Eastern Anatolia” (500 kg per stere assumption, 266 kg for Scots pine); Turkish State Meteorological Service official statistics, İzmir and Erzurum (monthly mean temperature); Turkish Coal Enterprises, “Coal Use in Stoves” (top-down lighting, 112); Ministry of Health, “Carbon monoxide poisoning”; U.S. CDC, “About Carbon Monoxide Poisoning”. Calorific values are from product bag statements; the table is arithmetic.