TTConverter is a VBA based tool that takes TH files (2G DC SQUID magnetometer) and jr6 files (AGICO JR-6 spinner magnetometer), converts them to the same format, combines them and finally writes them as TDT files for ThellierTool 4.0 (Leonhardt et al., 2004). As Thellier-Thellier can be quite frustrating, especially if some steps were measured on the cryo and some on the spinner, this tool will potentially save you not just a lot of time, but also a lot of frustration.

How it works:

  • Import or copy-paste your TH file(s) to the ‘TH’ sheet. If you want to convert multiple TH files at once, make sure to remove the last line (“END”) of all files except the last one and the first line (name of the operator) of all files except the first one.
  • Import or copy-paste your jr6 file(s) to the ‘jr6’ sheet.
  • Enter your steps into the ‘steps’ sheet in the ThellierTool 4.0 format (or if you’re using the IZZI protocol: use TTChecklist to create your list of step codes):
    • .00 for zero-field steps (e.g. 0.00 for the NRM)
    • .11 for in-field steps (e.g. 100.11 for an in-field step at 100 degrees)
    • .12 for pTRM checks (e.g. 100.12 for a pTRM check at 100 degrees)
    • .13 for pTRM tail checks (e.g. 300.13 for a tail check at 300 degrees)
  • Hit ‘Combine & convert’ in the ‘steps’ sheet to run the macro. You will be prompted for the laboratory field. If any duplicate steps were detected and removed, you will see a warning.
TTConverter 'steps' sheet. After clicking 'Combine & convert' you're prompted for the lab field.

TTConverter ‘steps’ sheet. After clicking ‘Combine & convert’ you’re prompted for the lab field.


  • Use the same step names in the TH file (e.g. 1 to 33) and the jr6 file (e.g. T1 to T33, i.e. choose ‘thermal demag’). ‘NRM’ in the jr6 file will be automatically converted to step number 1, and all Ts in the jr6 file step names are removed.
  • Check for duplicate measurements beforehand. TTConverter will detect and remove those, but it may not always remove the correct measurement. Check the ‘checks’ sheet to see for which samples duplicate measurements were detected and deleted.


  • Use sample names that Excel can interpret as dates (e.g. 1-2, 24-5). Use 1-2A or 1-2_ instead (etc.). Dates for sample names tend to freak out the code. (Or make sure the first column is read as something != a date.)
  • Entirely skip steps, as this will result in the ThellierTool step codes ending up at the wrong lines in your output file. (You’ll get a warning if this happens, assuming you numbered your steps as 1, 2, 3, etc.) It’s better to duplicate the previous/next line and remove this line after the conversion. This way you can be sure every step gets the correct ThellierTool code.

Download TTConverter here!

TTConverter 'checks' sheet. This sheet shows possible missing measurements and/or duplicate measurements.

TTConverter ‘checks’ sheet. This sheet shows possible missing measurements and/or duplicate measurements.


PhD candidate at Utrecht University and VU University Amsterdam, the Netherlands.

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