Pricing in the flexible environment

Much like the standard environment, pricing in the App Engine flexible environment is based on the total amount of running time for all instances. Unlike the standard environment, services running on the flexible environment are billed per second, and rates are based on the underlying virtual machine instances your applications run on.

Rates for the underlying VMs are determined by CPU, memory, and disk size. Each of these resources can be customized via the application configuration file to fit the specific needs of a service. As with Compute Engine, the rates for VM resources varies somewhat between regions.

One thing to note when comparing pricing between the standard environment and the flexible environment is that, due to slow startup times, the flexible environment is not able to effectively scale down to zero instances. This means that a service running on the flexible environment will need at least one instance running at all times. For services that experience long periods of inactivity, this difference in cost can be significant.