Spot Instances are only interrupted about 5% of the time on average, although this ratio varies significantly based on the Availability Zone and instance type.  Checking the frequency of interruption when going through the available instances is a smart move. The frequency at which the instance regained capacity during the preceding month is called the frequency of interruption. If you’re using AWS, take a look at Amazon's Spot Instance Advisor to get a rough idea of how often you may expect interruptions. It displays that frequency in ranges of <5%, 5-10%,10-15%,15-20% and >20%.