Actually, log changes are not linear. In other words, the difference between log7 and log6 is from 10 million to 1 million. from log6 to log5 is from 1 million to 100 000. From log 5 to log4 is from 100000 to 10000, and so on. In my case the viral load went from log 7.16 which is equivalent to 14,700,000 IU/ml to log6.7 which is 5,100,000 IU/ml. This means that my viral load went down by approximately two thirds. I have read that the virus normally fluctuates up to 0.75 logs. In my case a normal fluctuation is between 14,700,000 down to 2,600,000. If, for example, my viral load would have gone down to 2,000,000 then I would have known that I was on the right track.
An easy way to calculate logs is in excel, the function is =LOG10. So for 800,000 you would put =LOG10(800000) which would give you log 5.9. If you put =LOG10(50000) you get log 4.7