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NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP): Version 10

Please be advised that we no longer accept purchase orders under $2500.00.

Download REFPROP 10: $325.00 PLACE ORDER with credit card.

Upgrades are available from 9.x to 10.x. $125.00  UPGRADE with credit card.

Contact customer support at (844) 374-0183 (Toll Free) or for site licenses and distributor agreements.

  • Site licenses are available for REFPROP version 10.
  • Distributor agreements are available to integrate REFPROP into your software and hardware products.

See the REFPROP FAQ for help installing and using REFPROP.

For information on Refprop in Japanese, see

New Features of REFPROP Version 10

  • Enhancements have been made to most areas of the NIST REFPROP program, including the equations of state for many of the pure fluids and mixtures, the transport equations, the graphical interface, the Excel spreadsheet, the Fortran files (i.e., core property routines), the sample programs in Python, C++, MATLAB, VB, etc. Some of the more important improvements are listed below:
  • A new Excel file with many more examples and additional documentation.
  • All of the Fortran code was highly optimized resulting in increased calculation speed and improved convergence.  Many new flags were added to allow the user to specify better how the programs works.
  • A new function is available to allow users to call Refprop with one single command that replaces most other calls from 9.1 (thus removing the need to learn what routines to use and the inputs/outputs for each routine, such as TPFLSH, THERM, etc.)  However, the old routines are still available for backwards compatibility.
  • New shortcut keywords to load fluids and mixtures and other methods to simplify use of the code.
  • New shared library for the Mac; this allows use of Refprop with, for example, Python or Excel 2011.  A CMake‑based build system allows for compilation on any platform (windows, OSX, Linux).
  • The vapor‑liquid equilibrium calculations for tracing isotherms and isobars (T‑x and p‑x diagrams) are greatly improved (doi:
  • New reference equations of state for ammonia, helium, and heavy water.  The ammonia equation of state introduces the first change to the Helmholtz energy functional form in over 25 years of development of equations for the thermodynamic properties of fluids.
  • The addition of the following refrigerants:  R1123, R1224yd(Z), R1233zd(E), R1234ze(Z), R1243zf, and R1336mzz(Z).
  • The addition of the following fluids:  1,3‑butadiene, 1‑butyne, 1‑pentene, 2,2‑dimethylbutane, 2,3‑dimethylbutane, 3‑methylpentane, acetylene, chlorine, chlorobenzene, cyclobutene, 1,2‑dichloroethane, diethanolamine, docosane, ethylene glycol, ethylene oxide, hexadecane, monoethanolamine, perfluorohexane, propadiene, propylene oxide, and vinyl chloride.
  • New equations of state have been developed for cyclopentane, D4, heptane, hexane, hydrogen chloride, MDM, MD2M, MM, neon, octane, pentane, perfluorobutane, perfluoropentane, R‑1233zd(E), R‑161, R‑245fa, R‑E347mcc (HFE‑7000), and sulfur dioxide.  The development of an equation of state is a complex process requiring many months of work for each one.
  • Mixture model of Gernert implemented for selected mixtures with water, including water+CO2 and moist air.
  • Transport equations have been added or modified for acetone, acetylene, ammonia, benzene, butane, 1,3‑butadiene, 1‑butene, 1‑butyne, 2,2‑dimethylbutane, 2,3‑dimethylbutane, carbon dioxide, carbon monoxide, carbonyl sulfide, chlorine, chlorobenzene,  cis‑butene, cyclobutene, cyclohexane, cyclopentane, cyclopropane, D4, D5, D6, 1,2‑dichloroethane(R150), diethanolamine, diethyl ether, dimethyl carbonate, dimethyl ether, docosane, ethane, ethylbenzene, ethylene, ethylene glycol, ethylene oxide, fluorine, heptane, hexane, hexadecane, hydrogen chloride, hydrogen sulfide, isobutene, isohexane, isooctane, isopentane, krypton, methyl palmitate, methyl linolenate, methyl linoleate, methyl oleate, methyl stearate, m‑xylene, MD2M, MD3M, MD4M, MDM, MM, methylcyclohexane, 3‑methylpentane, monoethanolamine, neon, neopentane, nitrous oxide, Novec‑649, o‑xylene, p‑xylene, pentane,1‑pentene, propadiene, propylcyclohexane, propylene, propylene oxide, propyne, perfluorobutane, perfluoropentane, perfluorohexane, propane, R1123, R143a, R114, R161, R1224yd(Z), R1233zd(E), R1234yf, R1234ze(Z), R1234ze(E), R1243zf, R13I1 (CF3I), R1336mzz(Z), R218, R236fa, R236ea, R245ca, R245fa, R365mfc, RE143a, RE245cb2, RE245fa2,RE347mcc, RC318, R40, sulfur dioxide, trans‑butene, toluene, undecane, vinyl chloride, and xenon.
  • New mixture models for ammonia + water and ethylene glycol + water.
  • Approximately 400 binary pairs have been added from the work of Bell and Lemmon (doi: ) • Mixture parameters were fitted (or refitted) for the following binary mixtures:  R1234yf with R32, R125, R134a, and R1234ze(E), R1234ze(E) with R125 and R134a, and many others.  These new mixing parameters with R1234yf and R1234ze(E) are currently the standard used in the refrigeration industry and Version 10 puts all users in compliance with the property values now in use world‑wide.  All new ASHRAE predefined mixtures except those with trans‑1,2‑dichloroethylene (t‑EDC) (due to the lack of a pure fluid equation) are included.
  • New estimation schemes were developed for selected families of binary mixtures (n‑alkane + n‑alkane mixtures, mixtures with CO2, etc.) to obtain estimated interaction parameters for mixtures that have not been fitted.
  • A reverse Polish type notation was added to read any functional form for the transport properties, eliminating the need to compile a new DLL as new correlations are published.  The notation and corresponding coefficients of the equation are simply added to the fluid files and the new code will read and interpret the supplied text.
  • The DOI for each primary equation was added to the fluid files.  A link in the GUI is now available to load the publication if access to the journal is available.
  • Henry's constant estimation scheme to obtain better starting values for VLE of mixtures to improve convergence.
  • Additional code to identify type III mixtures for use in phase determination.
  • Most surface tension equations for the pure fluids have been updated, and an improved surface tension model for mixtures was added.
  • New code to calculate heat of formation or the mass flux for a Venturi nozzle.

Version 10.0 includes 147 pure fluids, 5 pseudo-pure fluids (such as air), and mixtures with up to 20 components:

  • The typical natural gas constituents methane, ethane, propane, butane, isobutane, pentane, isopentane, hexane, isohexane, 2,2-dimethylbutane, 2,3-dimethylbutane, 3-methylpentane, heptane, octane, isooctane, nonane, decane, undecane, dodecane, carbon dioxide, carbon monoxide, hydrogen, nitrogen, and water.
  • The hydrocarbons 1,3-butadiene, 1-butene, 1-butyne, 1-pentene, acetone, acetylene, benzene, butene, cis-butene, cyclobutene, cyclohexane, cyclopentane, cyclopropane, docosane, ethylene, hexadecane, isobutene, methylcyclohexane, neopentane, propadiene, propylcyclohexane, propyne, toluene, and trans-butene.
  • The HFCs R23, R32, R41, R125, R134a, R143a, R152a, R161, R227ea, R236ea, R236fa, R245ca, R245fa, R365mfc, R1123, R1224yd(Z), R1233zd(E), R1234yf, R1234ze(E), R1234ze(Z), R1243zf, and R1336mzz(Z).
  • The refrigerant ethers RE143a, RE245cb2, RE245fa2, and RE347mcc (HFE-7000).
  • The HCFCs R21, R22, R123, R124, R141b, and R142b.
  • The traditional CFCs R11, R12, R13, R113, R114, and R115.
  • The fluorocarbons R14, R116, R218, R1216, C4F10, C5F12, C6F14, and RC318.
  • The "natural" refrigerants ammonia, carbon dioxide, propane, isobutane, and propylene.
  • The main air constituents nitrogen, oxygen, and argon.
  • The noble elements helium, argon, neon, krypton, and xenon.
  • The cryogens argon, carbon monoxide, deuterium, krypton, neon, nitrogen trifluoride, nitrogen, fluorine, helium, methane, oxygen, normal hydrogen, parahydrogen, and orthohydrogen.
  • Water (as a pure fluid, or mixed with ammonia).
  • Ethylene glycol (as a pure fluid, or mixed with water).
  • The fluids carbonyl sulfide, chlorine, chlorobenzene, dichloroethane, diethanolamine, diethyl ether, dimethyl carbonate, dimethyl ether, ethanol, ethylene oxide, heavy water, hydrogen chloride, hydrogen sulfide, methanol, methyl chloride, monoethanolamine, nitrous oxide, Novec-649, propylene oxide, sulfur dioxide, sulfur hexafluoride, trifluoroiodomethane, and vinyl chloride.
  • The xylenes m-xylene, o-xylene, p-xylene, and ethylbenzene.
  • The FAMES (fatty acid methyl esters, i.e., biodiesel constituents) methyl oleate, methyl palmitate, methyl stearate, methyl linoleate, and methyl linolenate.
  • The siloxanes octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, decamethyltetrasiloxane, dodecamethylpentasiloxane, tetradecamethylhexasiloxane, octamethyltrisiloxane, and hexamethyldisiloxane.
  • 121 predefined mixtures (such as R407C, R410A, and air); the user may define and store others.

The program uses the most accurate equations of state and models currently available: 

  • High accuracy Helmholtz energy equations of state, including international standard equations for water, R134a, R32, and R143a and equations from the literature for ethane, propane, R125, ammonia, carbon dioxide, and others. 
  • High accuracy MBWR equations of state, including the international standard EOS for R123. 
  • The Bender equation of state for several of the "older" refrigerants, including R14, R114, and RC318. 
  • An extended corresponding states model for fluids with limited data. 
  • An excess Helmholtz energy model for mixture properties.
  • Experimentally based values of the mixture parameters are available for hundreds of mixtures.
  • The American Gas Association equation AGA8 for natural gas properties (as an alternative to the Helmholtz model).
  • Viscosity and thermal conductivity are based on fluid-specific correlations (where available), a modification of the extended corresponding states model, or the friction theory model.

Available properties: 

  • Temperature, Pressure, Density, Energy, Enthalpy, Entropy, Cv, Cp, Sound Speed, Compressibility Factor, Joule Thomson Coefficient, Quality, 2nd and 3rd Virial Coefficients, 2nd and 3rd Acoustic Virial Coefficients, Helmholtz Energy, Gibbs Energy, Heat of Vaporization, Fugacity, Fugacity Coefficient, Chemical Potential, K value, Molar Mass, B12, Thermal Conductivity, Viscosity, Kinematic Viscosity, Thermal Diffusivity, Prandtl Number, Surface Tension, Dielectric Constant, Gross and Net Heating Values, Isothermal Compressibility, Volume Expansivity, Isentropic Coefficient, Adiabatic Compressibility, Specific Heat Input, Exergy, Gruneisen, Critical Flow Factor, Excess Values, dp/dr, d2p/dr2,  dp/dT, dr/dT, dp/dr, d2p/dr2 

Windows®-based, graphical user interface features: 

  • The fluid or mixture, units, reference state, properties to be displayed, and other options are specified via pull down menus. 
  • A wide variety of tables - in a scrollable, spreadsheet style format - may be calculated, including saturation properties (with temperature, pressure, density, enthalpy, entropy, composition, or quality as the independent variable) and tables at constant temperature, pressure, density, volume, enthalpy, or entropy (with temperature, pressure, or density varied). 
  • Input properties may be read from a file. 
  • Data in any table can be copied to the clipboard for export to other programs (such as spreadsheets). 
  • Data in any table can be plotted. 
  • A wide variety of property diagrams may be automatically generated, including pressure-enthalpy and temperature-entropy diagrams and (for binary mixtures) temperature-composition and pressure-composition plots. 
  • User preferences and entire sessions may be stored for later use. 
  • A fluid search dialog is available to find fluids that match a certain criteria. 
  • A complete help system is available.

Source code: The FORTRAN subroutines and associated fluid data files are provided for those wishing to access REFPROP calculations from their own applications.

Excel spreadsheets:  A sample spreadsheet is included that demonstrates how the REFPROP DLL can be linked to Excel. Most properties that are available in the graphical interface can also be calculated in the spreadsheet.

Click here to view the PDF version of Users' Guide.

System Requirements: PC running Windows® XP, 7, 8, or 10; 10.0 MB available hard disk space.

For additional information contact:

For all issues related to ordering the program contact

For questions concerning the installation and running the program, with linking the program with other applications, or with issues concerning the fluid properties, please visit the FAQ site first:

Further answers can be found at GitHub: .  Please use this site to post new questions as well so that all REFPROP users may learn from the correspondence.  If you still need assistance, or have other matters that that you need to discuss, email


Keywords: air; alternative refrigerants; CFC; chemical engineering; chemistry; chlorofluorocarbons; cryogens; hydrochlorofluorocarbons; equation of state; fluids; hydrocarbons; HCFC; HFC; mixtures; natural gas; refrigerants; thermodynamic property; thermodynamics; thermophysics; transport property

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Created April 18, 2013, Updated June 2, 2021