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X Steam, Thermodynamic properties of water and steam.

version 1.0 (192 KB) by

Water properties A complete IAPWS IF-97 standard.

57 Ratings



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Editor's Note: This file was selected as MATLAB Central Pick of the Week, Steam and water properties for Matlab based on the "International Association for Properties of Water and Steam Industrial Formulation 1997 (IAPWS IF-97). A full implementation of the IF-97 standard that provides very accurate steam and water properties in ranges from 0-1000 bar and 0-2000°C. Provided thermodynamic properties are:

Specific volume
Specific entropy
Specific internal energy
Specific isobaric heat capacity
Specific isochoric heat capacity
Speed of sound
Vapour fraction

All properties can be calculated with the inputs, p and T known, p and h known, h and s known and some with pressure and density known. X Steam are a full implementation of the IF-97 formulation including all regions and all backward functions for good calculation speed. The code are speed optimized with pressure and enthalpy as inputs for dynamic simulations.

XSteam('h_pt',1,20) return the enthalpy of water at 1 bar and 20 degC. 84.0118 kJ/kg

XSteam('rho_ph',1,3000) return the density of steam at 1 bar and 3000 kJ/kg. 0.4056 kg/m3

XSteam('w_pt',1,20) returns the speed of sound at 1 bar and 20 deg C. 1483.4 m/s

XSteam('tSat_p',1) returns the saturation temperature at 1 bar. 99.6059 deg C

The X Steam Tables are the perfect tool both for replacing paper tables and for advanced calculations. The X Steam tables are open source and free of charge.

The X Steam tables are also available as MS Excel scripts, OOo Sripts, Dynamic Link Libary .DLL. Please visit

New version 2.5

Comments and Ratings (92)


BLE (view profile)

hi everyone, I have a problem using Xsteam for function call. X steam works fine when I use in matlab.m alone. But when I insert the matlab.m in simulink using user define matlab function, it fail to use function call of Xsteam to calculate.

X Steam, Thermodynamic properties of water and steam is an extremely useful function which allows one to compute many helpful thermodynamic quantities as a functions of specified parameters like pressure, enthalpy, entropy, and volume fractions. The code is robust and can return values from a wide range of initial inputs making this code useful in a many engineering design and analysis problems. This code has some minor user friendliness issues because it doesn't specify units or when the underlying equations are valid in each regions (It just returns NAN). There is insufficient commenting in the source code, so it was difficult to understand some of the developments. There are inconsistencies in the tolerance for the basic parameter calculation with while loops resulting in errors that are difficult to quantify. Errors are tabulated in an attached document, but there is not an overall significance level given. The code could be clearer and structured more logically to help users, but overall it is a good tool to calculate thermodynamic properties of water and steam.

Hello everyone,

Is there any Fluid-Gas table available? I am not dealing with pure water, and my system contains, sometime air, sometime steam and sometimes both. I would like to know if it is possible to have a Fluid-gas table?

Yash Trivedi

When I run the program it says
>> XSteam(fun, In1, In2)
Undefined function or variable 'fun'.
What can be the problem?

Bosong Lin

I am new here but wishing to enjoy your service. However i am getting different value compare to what i have on hard copies of steam table or what have been stated above.
for example:
1) XSteam('TSat_p',1) =101.6943 instead of 99.6 as we all know?
2) XSteam('rho_ph',1,3000) =4.3661e-04 instead of 0.4056 kg/m3
3)XSteam('h_pt',1,20) = the answer is NaN......

What Could be the reasons? Please help

Maroua Rou

Great job!
Please, can this program be extended for calculating thermodynamic properties of ice VII (from 2 to 20GPa) beyond 1000 bar?

Heil Hitler

Hello all,

The Code works perfectly when I send the Pressure and Temperature as Variables inside a Matlab function.
But when the same function is run by my Simulink Model, I get the Error saying "Expected a scalar. Non-scalars are not supported in IF or WHILE statements, or with logical operators. Instead, use ALL to convert matrix logicals to their scalar equivalents."

Could anyone please help me with this? Even though the Values of Pressure and Temperature are Scalar, I get this error.

Thank you,


My previous problem was solved. Turns out there is a difference in copy pasting an extracted folder and an extracted file into Documents/MATLAB

Great piece of code, extremely useful, can I have question? Can I get speed of sound for liquid-vapor mixture?

The function returns NaN.

Thank you :-)


i find the answer
>>just download the zipfile here and copy its files to matlab folder in documents or any path matlab use on computer

i can write it on matlab directly like

This is extremely helpful. Thank you :)

Good but it doesn't work foe temperatures above 800 C!

daniel perez

Ihab Farag

Mon. April 11, 2016
When I try to run xsteam.m in r2016a I get the following error about fun
Not enough input arguments.

Error in XSteam (line 221)
welcome help in fixing this error.

rouf awad

fun is undefined word!!

??? Input argument "fun" is undefined.

Peter Pauska

thank you for this code!
is it possible to use vectors as in1&in2? if I do this, I will get a error message:

'Operands to the || and && operators must be convertible to logical scalar values.'

Is there any way to calculate or determine the Isentropic Expansion Exponent?


simone (view profile)

I need the density of steam in the T interval 1273 K-1873 K and P 0.1-300 MPa. XSteam provides desnity for T up to 2000 C but for P<100 bar. Any suggestion?

Mark Mikofski

Mark Mikofski (view profile)

If you are looking for an alternative to XSteam, please consider - - it is vectorized, more current, and documented here:

Hello Sir,
I wanna know the function Xsteam use as input value SI values, because in the pdf theres is a table with the units but i dont know if they are units of the input or the outputs.



is showing as NaN. Please let me know the reason.

Not only density but all other properties are being shown as NaN

Tarek Sobh

Thank you Magnus for this. I would like to use this with Simulink, however, I'm not able to.. The code I'm using is as follows but I'm getting errors:

function h10 = fcn(t10)

Would appreciate if anyone can help.


I can not connect to x steam site. Got the following error message:

Oops! Internet Explorer could not connect to
Try reloading: www.­x-­eng.­com


Mark Mikofski

Mark Mikofski (view profile)

You might be able to increase speed for long loops by calling XSteam using arrayfun ( or use IAPWS_IF97 (

Mark Mikofski

Mark Mikofski (view profile)

@Daniel Vecchio - you might try NIST Chem WebBook (, EES from the University of Wisconsin (, TRNSYS also from Wisconsin ( or Aspen ( Good luck and post your findings to help others.

Hello, Excellent material!.

I'm looking for a similar tool to get the properties of refrigerants.
Do you know if there is something availbale?


Mark Mikofski

Mark Mikofski (view profile)

To get the help for both XSteam and XSteamUS, you need to open the source and delete the first three lines, or at least the blank lines. MATLAB will only return help using the first connected block of comments, but both XSteam and XSteamUS have a blank line after `%h_prho behöver T_prho för samtliga regioner!!!!` hence that is the only line returned as "help".

Mark Mikofski

Mark Mikofski (view profile)

Excellent resource, but would be better if vectorized and if it had thermodynamic derivatives for computational modeling.

Mark Mikofski

Mark Mikofski (view profile)

Open the source, look at lines 23-41, the units for each file are there


%*** Nomenclature ******************************************************************************************
% First the wanted property then a _ then the wanted input properties.
% Example. T_ph is temperature as a function of pressure and enthalpy.
% For a list of valid functions se bellow or XSteam for MS Excel.
% T Temperature (deg C)
% p Pressure (bar)
% h Enthalpy (kJ/kg)
% v Specific volume (m3/kg)
% rho Density
% s Specific entropy
% u Specific internal energy
% Cp Specific isobaric heat capacity
% Cv Specific isochoric heat capacity
% w Speed of sound
% my Viscosity
% tc Thermal Conductivity
% st Surface Tension
% x Vapour fraction
% vx Vapour Volume Fraction


Isaac (view profile)

using 'help XSteam' or 'help XSteamUS' does not output the units used:

>> help XSteamUS
h_prho behöver T_prho för samtliga regioner!!!!

>> help XSteam
h_prho behöver T_prho för samtliga regioner!!!!

I found the SI units in the pdf but how do I find out what the imperial units are?

Mark Mikofski

Mark Mikofski (view profile)

@AntoineTambue "XSteamUS" uses Imperial units, whereas "XSteam" (w/o "US") uses SI or metric units. Type `help XSteam` or `help XSteamUS` to see the units used.

Mark Mikofski

Mark Mikofski (view profile)

I know this is an oldie but goodie, and I greatly appreciate Magnus Holmgren's work. Therefore I humbly submit IAPWS_IF97.m ( which is inspired by XSteam, but completely reworked using IAPWS original to be vectorized and to include derivatives w.r.t. enthalpy and pressure. If you have comments on IAPWS_IF97.m, I would love to hear them. Thanks for your consideration.

Good tool

nathan q

nathan q (view profile)

Hello, There are two functions XSteam and XSteamUS. What is the difference between the two functions? I have tested the two functions and they give me different answers.


Ali (view profile)

the best tool ever used !


Leon (view profile)

Very good tool!
Excellent to have it condensed in a single .m file.

Manel Soria

Excellent !!


Rory (view profile)

Excellent work! You have made my life immeasurably easier with this great tool!


Vesa (view profile)

A remark Concerning my previous comment:
The code calculates tcL and tcV as it should.
Only the documentation is vice versa.


Vesa (view profile)

In 19.7.2006 "X Steam for Matlab.pdf" and in 4.5.2007 "XSteam.m" comment lines 139-142:
%tcL_p Saturated vapour thermal conductivity
%tcV_p Saturated liquid thermal conductivity
%tcL_T Saturated vapour thermal conductivity
%tcV_T Saturated liquid thermal conductivity

Should be;
%tcL_p Saturated liquid thermal conductivity
%tcV_p Saturated vapour thermal conductivity
%tcL_T Saturated liquid thermal conductivity
%tcV_T Saturated vapour thermal conductivity
, I guess?

Thomas Clark


Thank you for this thorough implementation with excellent help!


SooYoung Kang

Exactly what I needed, many thanks

Mariano Nemec

ciao Magnus,

I appreciated and used your excell worksheet many years ago (vers. 2.6).

there is a new version, and from where can I get it?

Dan Etenberg

Hello, the program is great, but I need to compute steam and ice values under 0ºC. Can anybody help me PLEASE?

How to use XSteam in Simulink?

Mark Mikofski

Mark Mikofski (view profile)

Thank you Magnus Holmgren for you outstanding work! Using your work as a inspiration, I completely re-coded all of the IAPWS IF97 (except region 5) and including some of the most recent documentation including thermodynamic derivatives which I needed for some non-linear 2-phase modeling. I have finally posted it here:
It is vectorized and fully tested, according to the test points in IF97 and accompanying documents and the numerous simulations I have performed using it. I hope you find it as useful as I have.

Morgan May

Very awesome, I was working on something similar myself, when i stumbled upon this. Talk about a time saver, I do have one question, in line 2496 Should the program read High_Bound = 2563.59200e+5 instead of High_Bound = 2563.592004+5?? Just curious.

Jason Wang

OMG. This program saves me so much time on each thermodynamics homework. Thanks so much!


Patrik (view profile)

Solid and precise, thank you.

aman brar

Awesome...This is exactly what I was looking for.

ashek ullah

So many thank for your information?

Xiangbin zhu

Thanks a lot!

William Hounks

Beau travail

Lourenco Crawford

very good!! thank you very much!

Lourenco Crawford

very good!! thank you very much!

Bogdan Marcu

Exactly what I needed, many thanks

Jonas Andersson

Just what I need

mario lebbe

Magnus Holmgren

Comment to review bellow. Temperature lines does off course break at the saturation line on ph diagrams. (However h_pt is not valid for mixtures of steam and water since temperature do not vary with enthalpy in that region. Answer becomes NaN. Temperature can?t be the saturation temp of p since then h is undefined.) I think you mixed up the numbers a little to.

XSteamUS('pSat_t',700) = 3.0928896229137e+03 psia
XSteamUS('hV_t',700) = 9.9063684424454e+02 btu/lb
XSteamUS('hV_p',3.0928896229137e+03) = 9.9063684424454e+02 btu/lb

Allan Zadiraka

Very happy to find steam properties as good as this. Saved me from having to create my own again. Only problem is the temperature lines not breaking at the saturation line on ph diagrams (in english units)at higher pressures; sat line at 3097 psia gives 989.2 BTU/Lb versus 981.5 BTU/Lb for 3097 psia and 700F.

David Andersson

Simple, exact.

mohammad kazemi

pippo pluto

Giovani Tonel

On line 1428 ==> err=check();

Jim Mechell

This is an extraordinary and excellent effort. In particular the ablity to obtain properties as functions P and h, h and s.
However it is not clear how the author has stated that properties can be found upto 2000 degree celcius if they are based on IF 97. These to my knowledge are applicable upto 800 degree celcius only. Students would still require a compact printed steam table that they can carry to a test or examination.An excellent new one called "Engineering Steam Tables"by Ashok Malhotra is now available for the purpose at (type the title in their search box to locae it)


I NEED HELP.................

Dave Abramovich

Very useful. Author must have had a lot of spare time, 150kb of code isn't a few hours job.

zhu jian

General Conmments

Poomjai Sa-adchom

I like this program

Jeff Buske

very nice piece of work! Well done.

Tamir Suliman

Great program and excellent structure.

Mike Baldea

Excellent work. Thank you.

donghui zheng

John McKenzie

Water data that really will save me a lot of work writing tables for interpolation into my program. A really great program!
I have two minor improvements:
- I would like the different functions as separate m files rather than commands.
- I agree with the previous reviewers that it would nice if the functions where vectorized.
However that?s minor problems, the program does what it?s supposed to and it?s simple to use and well structured. The program is worth a five star.

Duane Hanselman

1 star just to balance the author giving himself a 5 star rating. Thanks for the advice Urs!

urs (us) schwarz

it's ok - BUT (and this is a big BUT) - in the future, do NOT give your OWN submission(s) a rating of 5/5; some people might get really offended and nasty with this inappropriate behavior

Magnus Holmgren

I finally succeded in adding my file and I appriciate all the positive ratings the first day.
I'll consider to vectorize the functions.
The X Steam for MS Excel and the "spiffy figure" is also open source and can be downloaded from but I will add them to the ZIP file the next time I update it.

Johan Karlsson

Simple and gives exact accurate results.

John D'Errico

If you were to call this inside a long loop, the lack of vectorization might slow things down. However, thats the only reason why I might choose to downrate this at all. The documentation is far above average, so its still a 5 in my book.

urs (us) schwarz

really nice result of a project
- extraordinary help (including PDF, to boot)
it would be even nicer
- if it was vectorized
- if the spiffy figure could be reproduced easily (see above)
- if the ...XSteam macros for MS Excel... (as mentioned in the help section) came with the package
but this is just ranting a bit


New release with minor updates.

Update of unit error for function T_ps for mixture of steam and water.
Only important for english units.

Extensive testing.
Fixed missing ;.
Calling functions by pressure and density.

* English Units implemented!!!
* Fixed small error in region_ph speed up functions.
* my_ph not defined in region 4.

Version 2.2
* Added function:
* p_hrho
* Prandtl number added
* Extensive testing.
* Fixed error in Cp_ph

MATLAB Release
MATLAB 6.0 (R12)

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