Combustion of Fuels — Heating Values and Stoichiometry

Higher and lower heating values of common fuels, combustion stoichiometry, and air-fuel ratios.

combustionfuelsheatingvalues

Overview

The heating value (calorific value) of a fuel quantifies the energy released per unit mass during complete combustion. Two standard measures exist:

Higher Heating Value (HHV) — also called gross calorific value, includes the latent heat recovered by condensing water vapor in the combustion products back to liquid.
Lower Heating Value (LHV) — also called net calorific value, assumes water remains as vapor in the exhaust; this is the more relevant figure for most real-world combustion equipment.

The difference between HHV and LHV depends on the hydrogen content of the fuel, since hydrogen combustion produces water. Fuels rich in hydrogen (such as natural gas) show the largest gap between HHV and LHV.

Key Formulas

The relationship between higher and lower heating values for a hydrocarbon fuel can be estimated from the mass fraction of hydrogen:

LHV = HHV - h_{fg} \times \frac{9 \, w_H}{100}

where $h_{fg}$ is the latent heat of vaporization of water at 25 °C (approximately 2.442 MJ/kg), $w_H$ is the mass percentage of hydrogen in the fuel, and the factor 9 comes from the stoichiometric ratio of water produced per unit mass of hydrogen burned.

Variables

Symbol	Description	Typical Unit
HHV	Higher (gross) heating value	MJ/kg
LHV	Lower (net) heating value	MJ/kg
$h_{fg}$	Latent heat of vaporization of water at reference temperature	MJ/kg
$w_H$	Mass fraction of hydrogen in fuel	%

Fuel Heating Values

12 rows

Higher and lower heating values of common fuels at 25 °C reference temperature
Fuel	HHV(MJ/kg)	LHV(MJ/kg)	State
Hydrogen	141.8	120	Gas
Methane (natural gas)	55.5	50	Gas
Propane	50.3	46.4	Gas / Liquid
Butane	49.5	45.7	Gas / Liquid
Gasoline	46.4	43.4	Liquid
Kerosene	46.2	43	Liquid
Diesel	45.6	42.5	Liquid
Fuel oil (heavy)	42.5	39.5	Liquid
Ethanol	29.7	26.8	Liquid
Coal (anthracite)	32.5	31.5	Solid
Coal (bituminous)	30	28	Solid
Wood (dry)	20	18	Solid

Source: engineeringtoolbox.com

HHV Comparison

Higher and Lower Heating Values by Fuel

Restored Original Source Tables

The following tables are restored from the original source page to preserve the complete reference data.

Gaseous Fuels - Higher and lower calorific values (heating values)

6 rows

Gaseous Fuels - Higher and lower calorific values (heating values)
Gaseous Fuel	kg/m3(kg/m3)	g/ft3(g/ft3)	kWh/kg(kWh/kg)	MJ/kg(MJ/kg)	Btu/lb(Btu/lb)	MJ/m3(MJ/m3)	Btu/ft3(Btu/ft3)	kWh/kg(kWh/kg)	MJ/kg(MJ/kg)	Btu/lb(Btu/lb)	MJ/m3(MJ/m3)	Btu/ft3(Btu/ft3)
Acetylene	1.097	31.1	13.9	49.9	21453	54.7	1468
Ammonia				22.5	9690
Hydrogen	0.09	2.55	39.4	141.7	60920	12.7	341	33.3	120	51591	10.8	290
Methane	0.716	20.3	15.4	55.5	23874	39.8	1069	13.9	50	21496	35.8	964
Natural gas (US market)*	0.777	22	14.5	52.2	22446	40.6	1090	13.1	47.1	20262	36.6	983
Town gas						18	483

Source: engineeringtoolbox.com

Liquid Fuels - Higher and lower calorific values (heating values)

28 rows

Liquid Fuels - Higher and lower calorific values (heating values)
Liquid Fuel	kg/l(kg/l)	kg/gal(kg/gal)	kWh/kg(kWh/kg)	MJ/kg(MJ/kg)	Btu/lb(Btu/lb)	MJ/l(MJ/l)	Btu/gal(Btu/gal)	kWh/kg(kWh/kg)	MJ/kg(MJ/kg)	Btu/lb(Btu/lb)	MJ/l(MJ/l)	Btu/gal(Btu/gal)
Acetone	0.787	2.979	8.83	31.8	13671	25	89792	8.22	29.6	12726	23.3	83580
Butane	0.601	3.065	13.64	49.1	21109	29.5	105875	12.58	45.3	19475	27.2	97681
Butanol	0.81		10.36	37.3	16036	30.2	108359	9.56	34.4	14789	27.9	99934
Diesel fuel*	0.846	3.202	12.67	45.6	19604	38.6	138412	11.83	42.6	18315	36	129306
Dimethyl ether (DME)	0.665	2.518	8.81	31.7	13629	21.1	75655	8.03	28.9	12425	19.2	68973
Ethane	0.572	2.165	14.42	51.9	22313	29.7	106513	13.28	47.8	20550	27.3	98098
Ethanol (100%)	0.789	2.987	8.25	29.7	12769	23.4	84076	7.42	26.7	11479	21.1	75583
Diethyl ether (ether)	0.716	2.71	11.94	43	18487	30.8	110464
Gasoline (petrol)*	0.737	2.79	12.89	46.4	19948	34.2	122694	12.06	43.4	18659	32	114761
Gas oil (heating oil)*	0.84	3.18	11.95	43	18495	36.1	129654	11.89	42.8	18401	36	128991
Glycerin	1.263	4.781	5.28	19	8169	24	86098
Heavy fuel oil*	0.98	3.71	11.61	41.8	17971	41	146974	10.83	39	16767	38.2	137129
Kerosene*	0.821	3.108	12.83	46.2	19862	37.9	126663	11.94	43	18487	35.3	126663
Light fuel oil*	0.96	3.634	12.22	44	18917	42.2	151552	11.28	40.6	17455	39	139841
LNG*	0.428	1.621	15.33	55.2	23732	23.6	84810	13.5	48.6	20894	20.8	74670
LPG*	0.537	2.033	13.69	49.3	21195	26.5	94986	12.64	45.5	19561	24.4	87664
Marine gas oil*	0.855	3.237	12.75	45.9	19733	39.2	140804	11.89	42.8	18401	36.6	131295
Methanol	0.791	2.994	6.39	23	9888	18.2	65274	5.54	19.9	8568	15.8	56562
Methyl ester (biodiesel)	0.888	3.361	11.17	40.2	17283	35.7	128062	10.42	37.5	16122	33.3	119460
MTBE	0.743	2.811	10.56	38	16337	28.2	101244	9.75	35.1	15090	26.1	93517
Oils vegetable (biodiesel)*	0.92	3.483	11.25	40.5	17412	37.3	133684	10.5	37.8	16251	34.8	124772
Paraffin (wax)*	0.9	3.407	12.78	46	19776	41.4	148538	11.53	41.5	17842	37.4	134007
Pentane	0.63	2.385	13.5	48.6	20894	30.6	109854	12.6	45.4	19497	28.6	102507
Petroleum naphtha*	0.725	2.745	13.36	48.1	20679	34.9	125145	12.47	44.9	19303	32.6	116819
Propane	0.498	1.885	13.99	50.4	21647	25.1	89963	12.88	46.4	19927	23.1	82816
Residual oil*	0.991	3.752				41.8	150072	10.97	39.5	16982	39.2	140470
Tar*			10	36	15477
Turpentine	0.865	3.274	12.22	44	18917	38.1	136555

Source: engineeringtoolbox.com

Solid Fuels - Higher and lower calorific values (heating values)

12 rows

Solid Fuels - Higher and lower calorific values (heating values)
Solid Fuel*	kg/dm3(kg/dm3)	kWh/kg(kWh/kg)	MJ/kg(MJ/kg)	Btu/lb(Btu/lb)	kWh/kg(kWh/kg)	MJ/kg(MJ/kg)	Btu/lb(Btu/lb)
Anthracite coal		9.06	32.6	14015
Bituminous coal		8.39	30.2	12984	8.06	29	12468
Carbon		9.11	32.8	14101
Charcoal		8.22	29.6	12726	7.89	28.4	12210
Coke		7.22	26	11178
Lignite (brown coal)		3.89	14	6019
Peat		4.72	17	7309
Petroleum coke		8.69	31.3	13457	8.19	29.5	12683
Semi anthracite		8.19	29.5	12683
Sub-Bituminous coal		6.78	24.4	10490
Sulfur (s)		2.56	9.2	3955	2.55	9.2	3939
Wood (dry)	0.701	4.5	16.2	6965	4.28	15.4	6621

Source: engineeringtoolbox.com

Engineering Notes

Fuel Energy and LHV Estimate

Fuel mass(kg)

Higher heating value(MJ/kg)

Hydrogen by mass(%)

Useful efficiency(%)

Unit Converter

Fuel Heating Value Unit Converter

Heating value(MJ/kg)

Gas density(kg/m3)

Liquid density(kg/L)

Gas volume(m3)

Reference conditions — All tabulated values are at 25 °C and 1 atm. Heating values shift slightly with pressure and temperature; fuel gas standards (e.g., ISO 6976) specify exact correction procedures.
Moisture content — Solid fuels such as wood and coal vary widely in moisture and ash. The values shown assume reasonably dry, representative samples. Always use as-received or as-fired values for real equipment sizing.
Hydrogen effect — The HHV-to-LHV gap grows with hydrogen content. For natural gas (~25 % H₂ by mass), the difference is about 10 %. For coal (~4 % H₂), the difference is only 3–4 %.
Combustion efficiency — Condensing boilers can recover a portion of the latent heat, bringing effective efficiency closer to the HHV basis. Standard (non-condensing) appliances are rated on an LHV basis in many markets.
Unit conversion — 1 Btu/lb ≈ 2.326 kJ/kg. In US practice, heating values are commonly reported in BTU/lb or BTU/ft³; metric data uses MJ/kg or kJ/m³.

References

Engineering Toolbox — Fuels and Combustion

Source: engineeringtoolbox.com