The Guesstimate model isn’t great, you should look at the one on my spreadsheet instead. My most up-to-date estimate actually has a sigma of 0.56. It’s not actually a standard deviation, it’s the standard deviation of the log-base-10 of the distribution, which means the difference between the mean and one standard deviation above the mean is 0.56 orders of magnitude.
The Guesstimate model isn’t great, you should look at the one on my spreadsheet instead. My most up-to-date estimate actually has a sigma of 0.56. It’s not actually a standard deviation, it’s the standard deviation of the log-base-10 of the distribution, which means the difference between the mean and one standard deviation above the mean is 0.56 orders of magnitude.