Here are some posts I’ve found that help with quantifying the cost of downtime.
Hourly cost for computer networks - $42,000: http://www.networkworld.com/careers/2004/0105man.html?page=1
Cost per hour of datacenter downtime for large organizations - $1.13M: http://www.stratus.com/~/media/Stratus/Files/Library/AnalystReports/Aberdeen-4-Steps-Budget-Downtime.pdf
Average cost of a datacenter outage - $505,502: http://emersonnetworkpower.com/en-US/Brands/Liebert/Documents/White%20Papers/data-center-costs_24659-R02-11.pdf
Large enterprises lose more than $1M each year due to IT failures: http://www.informationweek.com/storage/disaster-recovery/it-downtime-costs-265-billion-in-lost-re/229625441
TechRepublic Article – How to calculate the cost of downtime: http://www.techrepublic.com/article/how-to-calculate-and-convey-the-true-cost-of-downtime/
Curious, what is your calculated hourly cost of downtime? What factors went into your calculation?