Coal Calorific Value Calculator

Work out coal calorific value instantly with clear inputs, formula shown and shareable results.

About Coal Calorific Value Calculator

Dulong's formula estimates gross calorific value from ultimate analysis: 8080C + 34,500(H - O/8) + 2240S in kcal/kg, with percentages by mass. Oxygen already combined with hydrogen contributes nothing, hence the O/8 deduction. Net calorific value subtracts the latent heat of the water formed from hydrogen.

Formulas

Dulong formula

GCV (kcal/kg) = 8080 C% + 34,500 (H% - O%/8) + 2240 S%, per 100

Net value

NCV = GCV - 2442 x (9 x H% / 100) kJ/kg

Worked example

With the default values below, Coal Calorific Value Calculator returns Gross Calorific Value of 6,124.8. Change any input above and every figure here is recalculated in your browser.

Inputs used

Carbonaccepts 0–100 %: 62 %
Hydrogenaccepts 0–30 %: 4.2 %
Sulphuraccepts 0–15 %: 0.5 %
Oxygenaccepts 0–40 %: 8 %

Results

Gross Calorific Value: 6,124.8
Gross Calorific Value In kJ/kg: 25,643.3
Net Calorific Value: 24,720.2
Available Hydrogen: 3.200

Step by step

1Values used
2Dulong formula
3Net value
4Gross Calorific Value= 6,124.8
5Gross Calorific Value In kJ/kg= 25,643.3
6Net Calorific Value= 24,720.2
7Available Hydrogen= 3.200

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How accurate is Dulong's formula?

Within about 2-3% for bituminous coals but poorer for lignites and high-oxygen fuels. A bomb calorimeter measurement should be used for contractual purposes.

Gross or net for boiler efficiency?

Both are used, but they must not be mixed. European practice generally uses net; North American practice uses gross. Efficiency quoted on net is several points higher for the same boiler.