The majority of resources available in Compute Engine carry some running costs, broken down into units that make sense for that type of resource. Basic instance resources include vCPU, RAM, and disk in terms of quantity and time. For predefined instances, this price is calculated in terms of machine type and size, as covered in the Machine types section earlier in this chapter. For custom machine types, the running costs of instances is determined in terms of raw compute resources.
Machines are charged in units of instance-hours on a per-second basis, with a minimum time of one minute. Being charged on a per-second basis makes it feasible to perform large-scale operations utilizing several machines for a short period of time. This is often ideal for highly-parallelized tasks.