Refrigerants & gases

Methane · CH4

Name: Methane (CH4) compressed-gas properties
Creator: ProcessConvert
License: https://creativecommons.org/licenses/by/4.0/

Methane (CH4, CAS 74-82-8) is an industrial and utility gas; this page gives its density, heat capacity and viscosity from 1 to 200 bar and -20 to 100 °C.

Values are computed from CoolProp==6.6.0 - reference Helmholtz equation of state for Methane (single-phase density, isobaric heat capacity and dynamic viscosity) and tabulated over 1–200 bar (absolute) and -20–100 °C.

Also known as: CH4, natural gas (pure component), marsh gas, R-50
CAS number: 74-82-8
Tabulated range: 1–200 bar · -20–100 °C

Identity

Molar mass: 16.043g/mol
Critical temperature: -82.59°C
Critical pressure: 45.992bar
Normal boiling point: -161.48°C

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, methane (CH4, CAS 74-82-8): molar mass, critical point and normal boiling point. https://webbook.nist.gov/cgi/fluid.cgi?ID=C74828&Action=Page

At 25 °C

reference snapshot

Density · 1 bar: 0.6483kg/m³
Density · 200 bar: 157.1kg/m³
Heat capacity · 1 bar: 2232J/kg·K
Viscosity · 1 bar: 11.196uPa.s
Compressibility · 200 bar: 0.824Z

Explore

Read a value at any pressure and temperature

Set a pressure (bar absolute) and a temperature (°C) to interpolate between the tabulated grid points. The readout and chart never go outside the validated 1–200 bar and -20–100 °C range, and every number is interpolated from the committed table below — nothing is computed from an equation of state in your browser.

Interactive explorer

Values are interpolated between the tabulated grid points below — pressure (bar absolute) and temperature (°C) stay within the validated 1–200 bar and -20–100 °C range and are never extrapolated.

Pressure (absolute)1 bar

Temperature25 °C

Density: 0.6483 kg/m³
Specific volume: 1.542 m³/kg
Compressibility Z: 0.9982
Heat capacity: 2232 J/kg·K
Viscosity: 11.196 uPa.s

Density (kg/m³) vs pressure (bar) for CH4 at 25 °C — Methane.

Full tables

Every tabulated point

Rows are temperature (°C); columns are pressure (bar absolute). Read the cell at the intersection. Density is the single-phase fluid density at that state.

Density — kg/m³

°C \ bar	1	2	5	10	20	50	100	200
-20	0.7645	1.5337	3.8699	7.8622	16.24	45.17	108.4	217.8
0	0.7081	1.4195	3.5740	7.2343	14.83	39.98	90.04	186.7
15	0.6709	1.3445	3.3811	6.8292	13.93	36.98	80.86	167.8
25	0.6483	1.2988	3.2639	6.5848	13.40	35.27	75.99	157.1
50	0.5979	1.1972	3.0045	6.0470	12.25	31.73	66.60	135.9
75	0.5547	1.1105	2.7840	5.5935	11.29	28.93	59.70	120.4
100	0.5174	1.0356	2.5941	5.2053	10.48	26.64	54.35	108.5

Isobaric heat capacity — J/kg·K

°C \ bar	1	2	5	10	20	50	100	200
-20	2149	2158	2186	2235	2345	2802	4009	4111
0	2181	2188	2211	2250	2335	2653	3370	3899
15	2210	2216	2236	2269	2341	2596	3125	3697
25	2232	2237	2255	2286	2350	2573	3018	3570
50	2293	2298	2313	2337	2388	2555	2865	3320
75	2365	2369	2380	2400	2442	2573	2804	3168
100	2443	2447	2457	2473	2507	2614	2795	3089

Dynamic viscosity — uPa.s

°C \ bar	1	2	5	10	20	50	100	200
-20	9.725	9.737	9.776	9.850	10.030	10.910	13.997	23.701
0	10.390	10.402	10.442	10.515	10.686	11.432	13.649	20.883
15	10.877	10.889	10.929	11.001	11.165	11.843	13.691	19.615
25	11.196	11.209	11.249	11.320	11.480	12.122	13.792	19.044
50	11.978	11.991	12.030	12.099	12.250	12.821	14.183	18.242
75	12.738	12.751	12.789	12.856	12.999	13.518	14.681	17.982
100	13.479	13.491	13.528	13.592	13.728	14.206	15.231	18.018

Typical values

Methane density at pressure (25 °C)

At 100 bar and 25 °C, methane density is about 76.0 kg/m³. At 200 bar and 25 °C, methane density is about 157.1 kg/m³.

Sources

Where the numbers come from

Every value on this page is computed by a deterministic equation of state — none is entered by hand. The generating method and the references it is checked against:

▸NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems (REFPROP-derived isothermal tables), methane (CAS 74-82-8)
▸CoolProp 6.6.0 - reference Helmholtz equation of state for Methane (Setzmann & Wagner, 1991); dynamic viscosity from the Quinones-Cisneros & Deiters, 2006 model

Model: CoolProp==6.6.0 - reference Helmholtz equation of state for Methane (single-phase density, isobaric heat capacity and dynamic viscosity) · Generated 2026-06-07

The committed data file for this page is published as JSON on GitHub under CC BY 4.0.

Validation

Checked against cited values

The equation of state is cross-checked against independently cited NIST WebBook reference points — a near-ambient and a compressed density, plus the heat-capacity and viscosity columns. The page is published only because every check passes.

Property / point	Density · 1 bar · 25 °C
Cited reference value	0.6483 kg/m3
Model computed	0.6483 kg/m3
Error vs reference	0% (tolerance 1%)

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, methane (CH4, CAS 74-82-8), isothermal table at 298.15 K: density at 1 bar = 0.64828 kg/m3. https://webbook.nist.gov/cgi/fluid.cgi?ID=C74828&Action=Page

Property / point	Density · 200 bar · 25 °C
Cited reference value	157.09 kg/m3
Model computed	157.0944 kg/m3
Error vs reference	0.003% (tolerance 1%)

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, methane (CH4, CAS 74-82-8), isothermal table at 298.15 K: density at 200 bar = 157.09 kg/m3. https://webbook.nist.gov/cgi/fluid.cgi?ID=C74828&Action=Page

Property / point	Isobaric heat capacity · 1 bar · 25 °C
Cited reference value	2231.6 J/kg.K
Model computed	2231.6 J/kg.K
Error vs reference	0% (tolerance 2%)

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, methane (CH4, CAS 74-82-8), isothermal table at 298.15 K: isobaric heat capacity Cp at 1 bar = 2231.6 J/kg.K. https://webbook.nist.gov/cgi/fluid.cgi?ID=C74828&Action=Page

Property / point	Dynamic viscosity · 1 bar · 25 °C
Cited reference value	11.076 uPa.s
Model computed	11.196 uPa.s
Error vs reference	1.085% (tolerance 2%)

NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, methane (CH4, CAS 74-82-8), isothermal table at 298.15 K: dynamic viscosity at 1 bar = 11.076 uPa.s. https://webbook.nist.gov/cgi/fluid.cgi?ID=C74828&Action=Page

Limitations

Before you use these numbers

▸CoolProp reference Helmholtz equation of state (Setzmann & Wagner, 1991) for methane; dynamic viscosity from the Quinones-Cisneros & Deiters, 2006 model. Single-phase density, isobaric heat capacity and dynamic viscosity, tabulated on a 1-200 bar (absolute) by -20 to 100 degC grid; two-phase, saturation and liquid states are out of scope for this page. The correlation is not extrapolated beyond the tabulated range. Values are for preliminary design; verify against vendor or reference data for critical service.
▸Every tabulated state is single-phase. A grid cell is left blank only where the state at that pressure and temperature would be two-phase or liquid - at or above the saturation pressure at that temperature - and the explorer will not interpolate across such a cell. Because the critical temperature of methane is -82.59 degC, below the -20 degC floor of this grid, every (pressure, temperature) point tabulated here is a supercritical single-phase fluid, so no cell is blank.
▸Values are tabulated only inside the 1–200 bar and -20–100 °C ranges shown; the equation of state is not extrapolated beyond them here.
▸Use for preliminary design; verify for critical service.

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