How can I accurately estimate the minimum resources my application needs?

Question

For an application that is starting out I do not want to over pay for servers and resources that will not be used since the budget is very limited at this point. This will be a for an iOS and Android productivity app.

What is the best way I can accurately estimate the resources and grow them based on the number of users I get on so I never have crashes because the server is over worked.

I'm thinking of having 25% of my needs but don't know how to go about getting what are my minimum requirements.

Answer 1

You don't make it clear in your question, but I'm assuming you're talking about server side resources from a cloud vendor such as Azure, Amazon AWS, etc.

The answer is to start as small as possible to prove your app works and so you know you're on the "I'm not spending enough" side of the performance curve.

Do some load testing and ramp up the concurrent users until something breaks or response time becomes unacceptably long.

Increase your server resources (either up to bigger machine(s) or out to a bunch of machines in parallel) and repeat the load testing as necessary.

There's no magic number (e.g. "25%") that will solve your problem for you - you'll just have to experiment and find the balance that's right for you between performance, available reserve, and cost.