Your computation is incorrect, 3 days out of 365 is 1% of downtime, not 0.1%. I believe your error stems from reporting .1% as 0.1. Indeed: 0.001 (.1%) * 8760

Your computation is incorrect, 3 days out of 365 is 1% of downtime, not 0.1%. I believe your error stems from reporting .1% as 0.1. Indeed: 0.001 (.1%) * 8760 (365d*24h) = 8.76h Alternatively, the common industry standard in infrastructure (the place I work at at least,) is 4 nines, so 99.99% availability, which is around 52 mins a year or 4 mins a month iirc. There's not as much room as you'd think! :)