Argon · Ar
Argon (Ar, CAS 7440-37-1) is an industrial and utility gas; this page gives its density, heat capacity and viscosity from 1 to 300 bar and -20 to 100 °C.
Values are computed from CoolProp==6.6.0 - reference Helmholtz equation of state for Argon (single-phase density, isobaric heat capacity and dynamic viscosity) and tabulated over 1–300 bar (absolute) and -20–100 °C.
- Also known as
- Ar, GAR, gaseous argon
- CAS number
- 7440-37-1
- Tabulated range
- 1–300 bar · -20–100 °C
- Molar mass
- 39.948g/mol
- Critical temperature
- -122.46°C
- Critical pressure
- 48.63bar
- Normal boiling point
- -185.85°C
NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, argon (Ar, CAS 7440-37-1): molar mass, critical point and normal boiling point. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7440371&Action=Page
- Density · 1 bar
- 1.6125kg/m³
- Density · 300 bar
- 486.6kg/m³
- Heat capacity · 1 bar
- 522J/kg·K
- Viscosity · 1 bar
- 22.624uPa.s
- Compressibility · 300 bar
- 0.993Z
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 1–300 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 1–300 bar and -20–100 °C range and are never extrapolated.
- Density
- 1.6125 kg/m³
- Specific volume
- 0.6202 m³/kg
- Compressibility Z
- 0.9994
- Heat capacity
- 522 J/kg·K
- Viscosity
- 22.624 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 | 300 |
|---|---|---|---|---|---|---|---|---|---|
| -20 | 1.9003 | 3.8055 | 9.5499 | 19.22 | 38.93 | 100.9 | 212.3 | 437.9 | 614.8 |
| 0 | 1.7606 | 3.5245 | 8.8358 | 17.75 | 35.83 | 91.86 | 190.0 | 386.2 | 550.1 |
| 15 | 1.6686 | 3.3397 | 8.3676 | 16.80 | 33.83 | 86.21 | 176.7 | 356.0 | 510.0 |
| 25 | 1.6125 | 3.2270 | 8.0825 | 16.21 | 32.62 | 82.86 | 168.9 | 338.8 | 486.6 |
| 50 | 1.4874 | 2.9760 | 7.4489 | 14.93 | 29.96 | 75.63 | 152.7 | 303.4 | 437.5 |
| 75 | 1.3804 | 2.7614 | 6.9085 | 13.83 | 27.72 | 69.66 | 139.8 | 275.8 | 398.3 |
| 100 | 1.2877 | 2.5758 | 6.4417 | 12.89 | 25.81 | 64.62 | 129.1 | 253.4 | 366.4 |
| °C \ bar | 1 | 2 | 5 | 10 | 20 | 50 | 100 | 200 | 300 |
|---|---|---|---|---|---|---|---|---|---|
| -20 | 522 | 524 | 529 | 539 | 558 | 623 | 745 | 933 | 960 |
| 0 | 522 | 523 | 528 | 536 | 551 | 602 | 692 | 840 | 890 |
| 15 | 522 | 523 | 527 | 534 | 547 | 590 | 665 | 790 | 845 |
| 25 | 522 | 523 | 526 | 533 | 545 | 584 | 651 | 763 | 818 |
| 50 | 521 | 522 | 525 | 530 | 540 | 571 | 623 | 711 | 763 |
| 75 | 521 | 522 | 524 | 529 | 537 | 562 | 604 | 675 | 721 |
| 100 | 521 | 522 | 524 | 527 | 534 | 556 | 590 | 649 | 689 |
| °C \ bar | 1 | 2 | 5 | 10 | 20 | 50 | 100 | 200 | 300 |
|---|---|---|---|---|---|---|---|---|---|
| -20 | 19.693 | 19.713 | 19.777 | 19.889 | 20.141 | 21.133 | 23.625 | 31.030 | 40.140 |
| 0 | 21.016 | 21.035 | 21.093 | 21.195 | 21.423 | 22.294 | 24.393 | 30.388 | 37.765 |
| 15 | 21.987 | 22.005 | 22.059 | 22.155 | 22.367 | 23.165 | 25.043 | 30.308 | 36.697 |
| 25 | 22.624 | 22.641 | 22.693 | 22.785 | 22.987 | 23.743 | 25.497 | 30.372 | 36.232 |
| 50 | 24.182 | 24.198 | 24.246 | 24.329 | 24.511 | 25.178 | 26.683 | 30.797 | 35.663 |
| 75 | 25.696 | 25.710 | 25.754 | 25.830 | 25.995 | 26.590 | 27.907 | 31.463 | 35.643 |
| 100 | 27.167 | 27.180 | 27.220 | 27.290 | 27.441 | 27.978 | 29.146 | 32.272 | 35.947 |
Argon density at pressure (25 °C)
At 100 bar and 25 °C, argon density is about 168.9 kg/m³. At 200 bar and 25 °C, argon density is about 338.8 kg/m³. At 300 bar and 25 °C, argon density is about 486.6 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), argon (CAS 7440-37-1)
- ▸CoolProp 6.6.0 - reference Helmholtz equation of state for Argon (Tegeler, Span & Wagner, 1999); dynamic viscosity from the Lemmon & Jacobsen, 2004 model
Model: CoolProp==6.6.0 - reference Helmholtz equation of state for Argon (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 | 1.6125 kg/m3 |
| Model computed | 1.6125 kg/m3 |
| Error vs reference | 0.001% (tolerance 1%) |
NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, argon (Ar, CAS 7440-37-1), isothermal table at 298.15 K: density at 1 bar = 1.6125 kg/m3. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7440371&Action=Page
| Property / point | Density · 300 bar · 25 °C |
| Cited reference value | 486.65 kg/m3 |
| Model computed | 486.6453 kg/m3 |
| Error vs reference | 0.001% (tolerance 1%) |
NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, argon (Ar, CAS 7440-37-1), isothermal table at 298.15 K: density at 300 bar = 486.65 kg/m3. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7440371&Action=Page
| Property / point | Isobaric heat capacity · 1 bar · 25 °C |
| Cited reference value | 521.5 J/kg.K |
| Model computed | 521.5 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, argon (Ar, CAS 7440-37-1), isothermal table at 298.15 K: isobaric heat capacity Cp at 1 bar = 521.54 J/kg.K. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7440371&Action=Page
| Property / point | Dynamic viscosity · 1 bar · 25 °C |
| Cited reference value | 22.624 uPa.s |
| Model computed | 22.624 uPa.s |
| Error vs reference | 0.001% (tolerance 2%) |
NIST Chemistry WebBook, SRD 69 - Thermophysical Properties of Fluid Systems. NIST Chemistry WebBook, SRD 69, Thermophysical Properties of Fluid Systems, argon (Ar, CAS 7440-37-1), isothermal table at 298.15 K: dynamic viscosity at 1 bar = 22.624 uPa.s. https://webbook.nist.gov/cgi/fluid.cgi?ID=C7440371&Action=Page
Before you use these numbers
- ▸CoolProp reference Helmholtz equation of state (Tegeler, Span & Wagner, 1999) for argon; dynamic viscosity from the Lemmon & Jacobsen, 2004 model. Single-phase density, isobaric heat capacity and dynamic viscosity, tabulated on a 1-300 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 argon is -122.46 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 1–300 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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