Issue
You have some questions regarding how you will be billed for Heroku's services.
Resolution
While the listed prices for Heroku products are given as monthly costs, we prorate all costs to the second.
For example, a Basic dyno costs $7/month. Running 1 Basic dyno costs roughly $0.25/day. If you use a Basic dyno for a Review App and scale the dyno to zero or delete the Review App in less than a day, it would cost you less than $0.25.
The monthly price for your resources is the maximum you are charged for those resources if you run them 24 hours a day, 7 days a week, since your last billing cycle.
Heroku invoices are generated each month for your usage of our services. For example, if you receive an invoice in February, it includes usage for the entire month of January's usage.
As a Personal account holder, and/or Team admin, you pay for usage accrued in the previous month. For help with reading your invoice, see this Knowledge Base article.
Heroku maintains a concise set of documentation in our Dev Center that addresses many questions related to usage & billing, as well as the billing cycle. Refer to the Dev Center for further information.
To keep track of your usage for the current month, look at Current Usage in the Billing Information section on your account's Billing tab.
Pricing Calculator
Use the Heroku pricing calculator to help compute costs to run your app on Heroku by selecting the number of dynos, data services, add-ons, Teams, CI/CD & Support to your estimate. Note that the calculator estimates using the full monthly cost of resources. In practice, all resources are prorated to the second, so resources used for Review Apps, CI, and other temporary use cases usually cost less than the full monthly price.