Calorific value of solid fuels: table and cost per kWh calculation

What calorific value is and why it is "net"

Calorific value is the amount of heat released by the complete combustion of one kilogram of fuel. Certificates give two figures: the gross value (Q_gr), measured in the laboratory and including the heat of condensation of water vapour, and the net value (Q_net), the working figure a boiler actually achieves, because the vapour goes up the chimney. To compare fuels and plan a season, use the net calorific value as received, i.e. at the moisture content the fuel has when it goes into the firebox.

Units: kcal, MJ, kWh

Price lists and certificates use three units. Converting between them is simple:

• 1 kWh = 860 kcal = 3.6 MJ
• 1 MJ = 239 kcal = 0.278 kWh
• 1,000 kcal = 4.19 MJ = 1.163 kWh

For household calculations kWh is the most convenient unit: it is what a house's heat loss and a boiler's output are measured in.

Calorific value table

Typical net calorific values for fuel at normal moisture. A specific batch may differ by 5-10%; the exact figure is in the quality certificate.

Fuel	Moisture	kcal/kg	MJ/kg	kWh/kg	Ash content
Anthracite AO, AM, AS	up to 8%	7,000-8,000	29-33	8.1-9.3	10-15%
Bituminous coal DG	up to 14%	5,500-6,500	23-27	6.4-7.6	10-20%
Bituminous coal G (Г)	up to 12%	6,000-6,800	25-28	7.0-7.9	10-20%
Brown coal B (Б)	up to 30%	3,000-4,500	12-19	3.5-5.2	15-30%
Wood pellets ENplus A1	up to 10%	4,000-4,300	16.5-18	4.7-5.0	up to 0.7%
Wood pellets A2	up to 10%	3,900-4,200	16-17.5	4.5-4.9	up to 1.2%
Sunflower husk pellets (agro pellets)	up to 12%	3,800-4,100	16-17	4.4-4.8	3-5%
RUF, Nestro briquettes	up to 10%	4,000-4,300	16.5-18	4.5-5.0	0.5-1.5%
Pini-Kay briquettes	up to 8%	4,100-4,500	17-19	4.8-5.2	up to 1%
Peat briquettes	up to 18%	3,000-3,900	12.5-16	3.5-4.5	8-15%
Firewood, oak, ash (dry, 20%)	20%	3,000-3,300	12.5-14	3.5-3.8	1-2%
Firewood, pine (dry, 20%)	20%	2,900-3,200	12-13.5	3.4-3.7	1-2%
Freshly cut firewood	45-55%	1,700-2,200	7-9	2.0-2.6	1-2%
Natural gas (for comparison)	-	8,000 kcal/m³	33.5 MJ/m³	9.3 kWh/m³	-

Moisture eats up heat

Every 10% of moisture takes away roughly 6-7% of the calorific value, because part of the heat is spent evaporating water. Freshly cut firewood at 50% moisture gives half as much heat as the same wood after two years under a shelter. This is the main reason why pellets and briquettes (moisture up to 10%) made from the same raw material heat twice as well as firewood: they are dried at the factory. Moisture is less critical for coal, but wet DG coal at 20% moisture instead of 12% also loses about 5% of its heat and is harder to light.

Boiler efficiency: how much heat reaches the radiators

Calorific value is the heat released in the firebox. Only part of it reaches the house, depending on the boiler:

Heating appliance	Efficiency
Pellet boiler with automatic controls	88-93%
Solid fuel boiler with forced draught and automatic controls	80-88%
Conventional solid fuel boiler	72-80%
Top-burning long-burn boiler	78-85%
Brick stove, masonry heater	55-70%
Potbelly stove, open fireplace	30-50%

So a tonne of anthracite in a forced-draught boiler delivers roughly 8,000 × 0.85 = 6,800 kWh to the house, while in an old stove it delivers only 8,000 × 0.6 = 4,800 kWh.

Cost per kilowatt-hour formula

To compare fuels in money terms, calculate the cost of one kilowatt-hour of useful heat:

Cost per kWh = price per tonne ÷ (calorific value in kWh/kg × 1000 × efficiency)

Below is a calculation based on market retail prices for September 2026 (Kyiv and Kyiv region, including delivery; see our catalogue for our own prices, which may differ) and current gas and electricity tariffs. This is an honest picture, not an advertising one: at this season's retail prices, solid fuel is not cheaper than gas and not always cheaper than electricity.

Fuel, tariff	Price, guide as of 09.2026	kWh per unit	Efficiency	Cost per useful kWh, UAH
Natural gas, household tariff	7.96 UAH/m³ (until 30.04.2027)	9.3 per m³	0.90	0.95
State firewood (the "ДроваЄ" program)	≈ 1,250 UAH per stacked m³	≈ 1,500 per m³ (dry)	0.75	1.1
Long-flame coal DG	9,000-11,000 UAH/t	7,000	0.78	1.65-2.0
Wood pellets, wholesale price from the manufacturer	8,000-13,000 UAH/t	4,800	0.90	1.85-3.0
Anthracite AO	13,500-18,000 UAH/t	8,500	0.80	2.0-2.65
RUF briquettes, mixed wood	9,000-12,000 UAH/t	4,800	0.78	2.4-3.2
Electric heating, discounted tariff	2.64 UAH/kWh (up to 2,000 kWh/month, 01.10-30.04)	1	1.00	2.64
Peat briquettes	7,000-12,000 UAH/t	4,000	0.78	2.25-3.85
Firewood, market price	3,700-4,500 UAH/m³	≈ 1,500 per m³	0.75	3.3-4.0
Wood pellets, retail with delivery	17,000-21,000 UAH/t	4,800	0.90	3.9-4.9
Electric heating, standard tariff	4.32 UAH/kWh (until 31.10.2026)	1	1.00	4.32

What follows from this. If the house has gas, it is the cheapest option, and no solid fuel at 2026 retail prices can beat it. If there is no gas and the electricity supply allows it, the discounted tariff of 2.64 UAH within 2,000 kWh per month is cheaper than retail pellets and briquettes and roughly on a par with coal - but the limit is only enough for a small insulated house, and above it the price is 4.32 UAH. DG coal, anthracite and pellets at wholesale prices (a pallet in summer, a big bag, bulk) come to 1.7-2.7 UAH, i.e. better value than electricity and considerably cheaper than retail pellets in autumn. So the main ways to save on solid fuel are not "choosing the cheapest type" but buying out of season and not at retail, and not overpaying per tonne by comparing bags of different weights.

Solid fuel wins regardless of prices where there is no gas and the electricity tariff limit is exceeded (a house over 120-150 m², old insulation), where there are power cuts, and in boiler houses that buy by the dozen tonnes. A comparison by convenience and boiler type is in the article "What to heat with: pellets, coal or briquettes".

How much fuel replaces a tonne of anthracite

A handy reference for estimating your stock. In terms of heat, one tonne of anthracite (about 8,500 kWh) corresponds approximately to:

• 1.2 tonnes of long-flame coal DG;
• 1.75 tonnes of wood pellets or briquettes;
• 2.1 tonnes of peat briquettes;
• 2.4 tonnes of dry firewood, i.e. about 6 stacked cubic metres of oak;
• 900 m³ of natural gas.

How to turn this into a season's requirement for a specific house is explained in the article "How much fuel you need per season", and you can calculate for your own floor area with the calculator on the pellets and coal pages.