Oxygen · O2
Oxygen (O2, CAS 7782-44-7) 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 Oxygen (single-phase density, isobaric heat capacity and dynamic viscosity) and tabulated over 1–200 bar (absolute) and -20–100 °C.
- Also known as
- O2, dioxygen, GOX, gaseous oxygen
- CAS number
- 7782-44-7
- Tabulated range
- 1–200 bar · -20–100 °C
- Molar mass
- 31.999g/mol
- Critical temperature
- -118.57°C
- Critical pressure
- 50.43bar
- Normal boiling point
- -182.96°C
NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, oxygen (O2, CAS 7782-44-7): molar mass, critical point and normal boiling point. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7782447&Action=Page
- Density · 1 bar
- 1.2917kg/m³
- Density · 200 bar
- 272.8kg/m³
- Heat capacity · 1 bar
- 920J/kg·K
- Viscosity · 1 bar
- 20.550uPa.s
- Compressibility · 200 bar
- 0.946Z
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.
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.
- Density
- 1.2917 kg/m³
- Specific volume
- 0.7742 m³/kg
- Compressibility Z
- 0.9993
- Heat capacity
- 920 J/kg·K
- Viscosity
- 20.550 uPa.s
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.
| °C \ bar | 1 | 2 | 5 | 10 | 20 | 50 | 100 | 200 |
|---|---|---|---|---|---|---|---|---|
| -20 | 1.5223 | 3.0485 | 7.6512 | 15.40 | 31.21 | 81.03 | 171.1 | 354.9 |
| 0 | 1.4103 | 2.8234 | 7.0786 | 14.22 | 28.72 | 73.71 | 152.8 | 311.8 |
| 15 | 1.3366 | 2.6753 | 6.7032 | 13.46 | 27.11 | 69.15 | 141.9 | 286.9 |
| 25 | 1.2917 | 2.5850 | 6.4747 | 12.99 | 26.14 | 66.44 | 135.7 | 272.8 |
| 50 | 1.1915 | 2.3839 | 5.9670 | 11.96 | 24.01 | 60.61 | 122.5 | 243.8 |
| 75 | 1.1057 | 2.2120 | 5.5338 | 11.08 | 22.21 | 55.81 | 112.0 | 221.3 |
| 100 | 1.0315 | 2.0633 | 5.1599 | 10.33 | 20.67 | 51.76 | 103.4 | 203.2 |
| °C \ bar | 1 | 2 | 5 | 10 | 20 | 50 | 100 | 200 |
|---|---|---|---|---|---|---|---|---|
| -20 | 915 | 918 | 925 | 937 | 963 | 1048 | 1210 | 1467 |
| 0 | 917 | 919 | 925 | 935 | 955 | 1022 | 1141 | 1340 |
| 15 | 918 | 920 | 925 | 934 | 952 | 1008 | 1107 | 1273 |
| 25 | 920 | 921 | 926 | 934 | 950 | 1001 | 1089 | 1238 |
| 50 | 924 | 925 | 929 | 935 | 949 | 989 | 1057 | 1173 |
| 75 | 929 | 930 | 933 | 938 | 949 | 983 | 1037 | 1130 |
| 100 | 935 | 935 | 938 | 943 | 952 | 980 | 1024 | 1101 |
| °C \ bar | 1 | 2 | 5 | 10 | 20 | 50 | 100 | 200 |
|---|---|---|---|---|---|---|---|---|
| -20 | 17.981 | 18.004 | 18.073 | 18.190 | 18.431 | 19.244 | 21.133 | 27.678 |
| 0 | 19.143 | 19.165 | 19.233 | 19.346 | 19.577 | 20.334 | 21.953 | 27.077 |
| 15 | 19.993 | 20.015 | 20.081 | 20.191 | 20.416 | 21.139 | 22.616 | 27.021 |
| 25 | 20.550 | 20.571 | 20.636 | 20.745 | 20.965 | 21.668 | 23.069 | 27.102 |
| 50 | 21.910 | 21.931 | 21.993 | 22.098 | 22.308 | 22.968 | 24.220 | 27.567 |
| 75 | 23.228 | 23.248 | 23.308 | 23.408 | 23.610 | 24.233 | 25.377 | 28.260 |
| 100 | 24.507 | 24.526 | 24.583 | 24.680 | 24.873 | 25.465 | 26.525 | 29.076 |
Oxygen density at pressure (25 °C)
At 100 bar and 25 °C, oxygen density is about 135.7 kg/m³. At 200 bar and 25 °C, oxygen density is about 272.8 kg/m³.
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), oxygen (CAS 7782-44-7)
- ▸CoolProp 6.6.0 - reference Helmholtz equation of state for Oxygen (Schmidt & Wagner, 1985); dynamic viscosity from the Lemmon & Jacobsen, 2004 model
Model: CoolProp==6.6.0 - reference Helmholtz equation of state for Oxygen (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.
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 | 1.2917 kg/m3 |
| Model computed | 1.2917 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, oxygen (O2, CAS 7782-44-7), isothermal table at 298.15 K: density at 1 bar = 1.2917 kg/m3. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7782447&Action=Page
| Property / point | Density · 200 bar · 25 °C |
| Cited reference value | 272.76 kg/m3 |
| Model computed | 272.7598 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, oxygen (O2, CAS 7782-44-7), isothermal table at 298.15 K: density at 200 bar = 272.76 kg/m3. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7782447&Action=Page
| Property / point | Isobaric heat capacity · 1 bar · 25 °C |
| Cited reference value | 919.6 J/kg.K |
| Model computed | 919.6 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, oxygen (O2, CAS 7782-44-7), isothermal table at 298.15 K: isobaric heat capacity Cp at 1 bar = 919.61 J/kg.K. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7782447&Action=Page
| Property / point | Dynamic viscosity · 1 bar · 25 °C |
| Cited reference value | 20.55 uPa.s |
| Model computed | 20.55 uPa.s |
| 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, oxygen (O2, CAS 7782-44-7), isothermal table at 298.15 K: dynamic viscosity at 1 bar = 20.55 uPa.s. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7782447&Action=Page
Before you use these numbers
- ▸CoolProp reference Helmholtz equation of state (Schmidt & Wagner, 1985) for oxygen; dynamic viscosity from the Lemmon & Jacobsen, 2004 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 oxygen is -118.57 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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