The price of App Engine consists of multiple factors and differs for Standard and Flexible environments. For Standard environment instances, running in manual and basic scaling services are billed at hourly rates based on uptime. For Flexible environments, the applications are deployed into virtual machine instances that are billed on a per-second with a minimum of 1 minute usage.
On top of that, you need to include the cost of additional resources that are used by your application. To get the most recent prices, take a look at the following link: https://cloud.google.com/appengine/pricing.
