Besides the simple Thiele-Small parameters, it can also assist you (the DIY speaker builder) in measuring loudspeaker parameters, and you can pick between the normal two methods (added mass or closed box). With the closed box method it uses a slightly improved Thiele-Small model where leakage loss is included, baffle load can be included as well, so you should get some really nice and reliable data. In DPC everything is documented, formulas, theory, everything. A newbie in loudspeakers could learn a lot from the documentation. DPC supports any kind of units you would like to apply - and files for UK and SI units are included. Take a look at this powerful little calculator, download DPC061.EXE, the version 0.6.1 installer package, compiled for Windows only (438 kb).
You can also download the version 0.5.0 archived as a ZIP file, DPC050.ZIP, with installer package, compiled for Windows only (1 Mb). You can also download DPC049.EXE, the version 0.4.9 (for DOS) archived as an LHARC compressed, self extracting file (180 kb). Alternatively check Brians DIYSUBWOOFERS page(s).
The manual for DPC release 0.6.1 is
available online. Please check it out.