How do I estimate what a small Catalyst app will cost each month?

Estimate it from the usage you expect for each component, because Catalyst bills each operation, such as a Data Store insert, a function’s execution time or an email sent, at its own unit price.

1. List the components your app will use and how much of each it needs in a month, for example Data Store reads and writes, function executions with their memory size, and storage.
2. Look up each operation’s unit price on the Catalyst Pricing page, and its free allowance on the Free Tier page.
3. On the pay-as-you-go model, subtract the free tier allowance, which is shared across your projects. Once your usage exceeds the free tier for any resource, each project with billable activity is billed at least USD 5 for the month.
4. On a subscription plan, choose a plan whose amount, plus the extra USD 5 that Catalyst adds in each billing cycle, covers your estimate.
5. When your app has run for a month, compare your estimate with Forecast in Settings → Billing → Overview.

Note: Catalyst Serverless Functions are priced per second of execution by memory size, and AppSail per minute of instance running time by memory size.

Refer to the Pricing Calculations help page and the Pay-As-You-Go Pricing Model help page for details.