In order to correctly convert frames into SMPTE timecodes, use the command line tool located in this folder: timecodeconvert.exe. This tool will allow for correct calculations on drop frame timecodes, which are very difficult to accurately calculated otherwise.

The tool allows an argument for the required framerate, including 25, 24df, 24ndf, 30df, 50, 60df and 60ndf. (DF = Drop Frame, NDF = No Drop Frame).

Example:
To find the time code for 100 frames at 24 drop frame, type the following: timecodeconvert.exe -24df 100.

You will then see the console read out: Frame number 100 is timecode 00:00:04:04.

More info on SMPTE can be found here - https://en.wikipedia.org/wiki/SMPTE_timecode

Advanced

If you need to run a batch job that obtains the total frame number from a CSV and passes it to the timecodeconvert.exe app, use the below in powershell:

$csv = Import-Csv C:\SMPTE\2997.csv
foreach ($line in $csv) {
.\timecodeconvert.exe -30df $line.frame
}

This will take the file at C:\SMPTE\2997.csv and, for each entry in the frame column, it will pass it through to timecodeconvert and print out the results. You can then use text to columns within Excel to extract the timecode values.