Accelerator Track Log Size - This a valid formula ?

I came across this as a formula to calculate the required space for the accelerator track log, it was old and in a non-authorative forum post . 

Is this still accurate?

Track Log Size [bytes] = [Number of files * 200] + [ [ Number of 128 KB blocks used ] *20 ]

I.E

Track Log Size [bytes] = [Number of files * 200] + [ [ Total disk space used in Bytes /128KB ] *20 ]

Cheers