Isoplot is BGC’s Visual Basic Add-in for Microsoft’s Excel ® for data analysis and graphical presentation of geochronology, earth science and other radiogenic isotope data only.

BGC’s Isoplot is not the Isoplot® for analysis of any measuring system as described at BGC is not affiliated with Red X® Holdings, LLC. Isoplot® is a registered trademark of Red X® Holdings, and is licensed to Shainin ® LLC.


Isoplot 3.7 and 4.1

Isoplot is a flexible tool for the mathematical and graphical interpretation of radiogenic-isotope data, especially as applied to geochronology.

Isoplot 3.7 and Isoplot 4.1 are “Add-In” programs that run only under Windows Excel versions 2003 and earlier (Isoplot 3.7), or only under Excel versions 2007 and 2010 (Isoplot 4.1). No versions of Isoplot can be run as a stand-alone program.

Isoplot 3 is not compatible with either Excel 2007 or Excel 2010. If you must use Excel 2007 or Excel 2010, request a copy Isoplot 4, which is compatible with Excel 2007/2010 only. Isoplot 4 has no more functionality than Isoplot 3.7, and somewhat less flexibility. Expect a speed penalty of up to a factor of 10 when using Excel 2007/2010.

There are no versions of Isoplot compatible with native Macintosh versions of Excel, including Excel 2011. To run Isoplot on the Macintosh, you will need to acquire a Windows-enabling program (Fusion will work, but not Crossover nor Parallels). Despite expectations on my part, Excel 2011 is not Isoplot-compatible


Isoplot can:

  • Calculate and plot classical isochrons (Rb/Sr, Sm/Nd, U/Pb, Re/Os, Lu/Hf…);

  • Construct U-Pb concordia plots and calculate ages using conventional  concordia intercepts, the “Concordia Age” algorithm, 3-D planar concordia intercepts, or 3-D linear (“Total U/Pb”) isochrons;

  • Calculate uranium-series isochron ages using 3-D or 2-D isochrons and construct 230Th/238U-234U/238U evolution curves and isochrons;

  • Plot Ar-Ar step-heating diagrams and find the statistically-best plateau steps and age;

  • Combine Ar-Ar isochron with Ar-Ar step-heating diagrams to obtain the logically optimum combination of both;

  • Use simple Bayesian constraints Improve the estimates and error-assignments for a package of stratigraphically-constrained radiometrically-dated units whose ages overlap within errors (with a special variant for 230Th/U ages);

  • Construct single-stage growth-curves for plots of com­mon-Pb data;

  • Construct cumulative-probability / histogram plots and linearized-probability diagrams;

  • Calculate both conventional (analytical-error weighted) and robust (nonparametric) x-y regressions for “classical” and Pb-Pb isochrons;

  • Deconvolute mixtures of components having Gaussian error-distributions using the Sambridge-Compston approach;

  • Calculate and construct plots for either error-weighted or robust (nonparametric) averages of a single variable;

  • Plot curves for almost any function;

  • Provide Monte Carlo errors as well as asymptotic (first-order) errors for most linear regressions, isochrons, and concordia-intercept solutions;

  • Extract reliable ages and errors from complex suites of Phanerozoic single-zircon dates;

  • Expand the number of Excel functions by more than 50, including many functions for radiogenic-isotopes (including 16 for U/Pb and 8 for 230Th-234U-238U alone).

Isoplot is available without charge.

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