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Thermodynamic Properties of Water: 

Tabulation from the IAPWS Formulation 1995 for the 

Thermodynamic Properties of Ordinary Water Substance for 

General and Scientific Use 

Allan H. Harvey 

Physical and Chemical Properties Division 

Chemical Science and Technology Laboratory 

National Institute of Standards and Technology 

325 Broadway 

Boulder, CO 80303 

Tables are provided for the density, enthalpy, entropy, and volume of water and 

steam calculated from the IAPWS Formulation 1995 for the Thermodynamic 

Properties of Ordinary Water Substance for General and Scientific Use. This 

formulation is the current international standard for water’s thermodynamic 

properties, and is implemented in NIST Standard Reference Database 10. The 

properties are tabulated along the vapor-liquid saturation curve as a function of 

both temperature and pressure. They are also tabulated for single-phase states on 

a grid of temperatures and pressures extending to 2000 oC and 1000 MPa. 

Key words: density; enthalpy; entropy; steam; steam tables; thermodynamic 

properties; volume; water 

1. Introduction

The current international standard for the thermodynamic properties of ordinary water is 

the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance 

for General and Scientific Use [1,2]. We will refer to this formulation as IAPWS-95. 

Unfortunately, the paper describing IAPWS-95 [2] has not yet been published, and there 

is to our knowledge no source of tabulated property values other than the small number of values 

given in the IAPWS Release [1] for the purpose of checking computer codes. While we 

anticipate that the needs of most users will be met by the software implementation of this 

formulation [3], there is still some demand for printed “Steam Tables.” The purpose of this 

report is to meet that demand, though this report may be superseded at a later time by a more 

thorough Steam Tables book such as the one that was produced for the previous standard by Haar 

et al. [4]. 
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2. Generation of the Tables

The numbers in these tables were generated from the Fortran code that implements the 

IAPWS-95 formulation in NIST Standard Reference Database 10, Version 2.1 [3]. They were 

then copied directly into tables in a word processing program. Most computed values were 

rounded to five significant digits. The number of digits printed for any value should not be taken 

as an indication of the accuracy of the formulation at that point; the IAPWS Release (reprinted as 

Appendix A) should be consulted for that information. 

These tables largely follow the example of Haar et al. [4]. However, in the 14 years since 

that book was published, the purpose of printed Steam Tables has changed. Users who need high 

accuracy for scientific research or industrial design will use software, not printed tables. The 

printed tables are now mainly useful for quick estimates and therefore need not be as finely 

spaced in their coverage of pressures and temperatures. For this reason, the largest table in this 

report (the single-phase table, Table 3) is somewhat less than half the size of the corresponding 

table in the book of Haar et al. The tables for saturation properties are also somewhat shorter. 

3. Notes on the Tables

In general, these tables should be self-explanatory. Standard notation (documented in the 

“List of Symbols”) has been used, and traditional formatting has been followed. Here, a few 

specifics which may not be obvious are described. 

In Table 3, the subcritical isobars cross the vapor-liquid saturation boundary. The first 

two lines printed for each isobar give the values of properties for the saturated liquid and 

saturated vapor, respectively. As is customary, a horizontal line is drawn between the points 

immediately above and below the phase boundary. 

The IAPWS-95 formulation is recommended for fluid states at temperatures up to 

1000 oC and 1000 MPa, and tests have shown it to extrapolate reasonably to higher temperatures 

and pressures and also to metastable liquid conditions at subfreezing temperatures at ambient 

pressures. (For more details on the range of validity and on extrapolation capabilities, consult the 

Release reprinted as Appendix A.) All points in Table 3 above 1000 oC should be considered 

extrapolations. Some of the low-temperature points in Table 3 correspond to conditions where 

the equilibrium phase would be a solid. For those points at low pressures, this is indicated by 

italicizing the values. At high pressures, these points are not printed at all since there is no way 

to verify the formulation’s accuracy at those conditions. The solid-fluid equilibrium boundaries 

were determined from the formulas given by Wagner et al. [5]. 

___________________ 

The author thanks the ASME Research and Technology Committee on Water and Steam 

in Thermal Power Systems, Subcommittee on Properties of Water and Steam, for advice and 

encouragement on this project. 
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4. References 

[1] Release on the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary 

Water Substance for General and Scientific Use, Fredericia, Denmark, 1996. This release 

is reproduced as Appendix A of this report; copies of this and other IAPWS releases may 

be obtained from the IAPWS Executive Secretary: Dr. R.B. Dooley, Electric Power 

Research Institute, 3412 Hillview Avenue, Palo Alto, CA, 94304, USA. 

[2] A. Pruß and W. Wagner, “The IAPWS Formulation 1995 for the Thermodynamic 

Properties of Ordinary Water Substance for General and Scientific Use,” to be submitted to 

J. Phys. Chem. Ref. Data. 

[3] A.H. Harvey, A.P. Peskin, and S.A. Klein, NIST/ASME Steam Properties, Natl. Inst. 

Stand. Technol. Standard Reference Database 10, Version 2.1 (1997). 

[4] L. Haar, J.S. Gallagher, and G.S. Kell, NBS/NRC Steam Tables, Hemisphere, New York 

(1984). 

[5] W. Wagner, A. Saul, and A. Pruß, “International Equations for the Pressure along the 

Melting and along the Sublimation Curve of Ordinary Water Substance,” J. Phys. Chem. 

Ref. Data 23, 515-527 (1994).