I’m the sole user of a my google app engine app. Currently I use approx 25% of my front end instance hours per day. Does this seem excessive ? Reason I’m asking is that if I begin to allow other user to use my app I will quickly exceed the daily quota ?
So if I add 3 more users that use exactly the same functionality I will use 100% of my front end instance hours. Is it this simple to calculate the cost of allowing multiple users to use my app ? If not how can I estimate the frontend Instance hours when app becomes mult-user based on current usage for one user?
You get enough front end hours to run your application 24/7. Even if you add 3 more users you’ll still only be at 100% which is fine. You can’t use “more” then 100% with a single instance plus you in fact get 28 instance hours a day free, not 24.
If you were to allow more instances to spin up then of course you can go over 100% (i.e. over the free quota).
To know the per user cost you can start with appstats.
The per-request cost can be calculated. Also you can use the header X-AppEngine-Estimated-CPM-US-Dollars as described in this question and the docs are here.
There is no way to answer questions like “does 25% hour usage per day per user seem reasonable” as it depends entirely on what your app does and how efficiently you have created it.