JPCalcW - Stand-alone Liquid Junction Potential Calculator

JPCalc  (Barry, 1994; J. Neurosci. Method., 51: 107-116) is a research/teaching program designed (1) to show graphically how junction potentials arise in a variety of different patch-clamp configurations and other electrophysiological situations; (2) to then enable the ready calculation of junction potential corrections, given the solution data, and (3) to show clearly how those junction potential corrections need to be applied to the appropriate physiological measurements [see review on junction potentials, J. Membrane Biol., 121, 101-117 (1991)].

The original JPCalc program has since been reprogrammed as a full Windows program  JPCalc for Windows, or JPCalcW, by Axon Instruments, Inc (Now part of Molecular Devices Corp.).  It is either available with their pClamp package, or as a stand-alone program from Professor Peter H Barry.  The cost of the JPCalcW software package on a CD, printed graphical Users' Manual and a laboratory license for multiple computers in the one lab/research group and cost of international express courier is A$175 (ex GST). Alternatively, an electronic version of the above package may be purchased for A$95 (ex GST).  In either case, from 2011, purchase is now organised via Professor Barry and payment is normally by credit card (VISA or MasterCard) to SDR Clinical Technology, Sydney (  So far JPCalc or JPCalcW has been purchased by more than 100 laboratories in at least 17 different countries.   This program should also run with Apple Macintosh computers provided they have a fully compatible Windows/DOS emulation package.   Further details can be obtained by e-mailing

While JPCalc for Windows (JPCalcW) will run under 32-bit Vista, Windows 7 and earlier Windows, it will NOT DIRECTLY run under 64-bit Windows, as is true of a number of other programsHowever, JPCalcW will run in XP-mode under 64-bit Windows, which can be obtained free for Windows 7.

To download a demonstration copy of the DOS version of JPCalc please click on JPCalc Demo Download.  Save the file on your computer, unzip the file and place all the component files together in a suitable folder (directory) on your HDD.

Although this DOS demo version will run under Windows (see below), it has significant limitations, which will restrict it from being used with most real experimental solutions.  To run the program do the following:

Under Windows XP and earlier, you can directly run the demo JPCalc.exe file, which will automatically extract the component files and then you can run JPCalc.exe directly. 

Under Windows 7 (32-bit and 64-bit) and Vista, JPCalc.exe can be run using a DOSBox program, that you can download from the internet free (e.g., using the 32-bit download option). Install the DOSBox program and place a short-cut to the DOSBox program on your desktop.  Open the folder with the  JPCalc.exe program and drag (with left click) the JPCalc.exe icon to the DOSBox short-cut icon. This will automatically run this JPCalc demo program in the DOS box. One warning - do not use the number pad with DOSBox.

For a view of the typical screen of the full Windows version of the program, JPCalcW, refer back to illustration on the home page.

To return to Liquid Junction Potential Calculator and LJP Calculations, or for other information about such calculations and mobility values, click here

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Peter H. Barry, Jan 24, 2014