Fee selection for transaction I have an application where I pay users in bitcoins (microtransactions). I am also starting to use Bitcoin core.

What I want:
Pay the minimum possible as fee of a custom transaction (1 input and x outputs). I need to pay the minimum because this difference is very important to make my app viable.

I saw that here are different costs/byte. And I see that 0 fee transactions can take forever. But my doubt is that if I pay a minimum of 1 to 10 Satoshis/byte, could the transaction be stucked for ever? or it will spent as maximum 240 min (as the page shows right now I know it can vary). 

I also "don't care" about the transaction time spends to reach its destination (to be confirmed) as much I would like 5 days more or less to confirm.

Questions:


Can it take forever if I pay the minimum or it will also be but in some days.
What minimum of fee / byte do you recommend me?


Thank you for reading!
If you don't understand something, please make me know and I'll try to explain better.
10 satoshis/byte would have gotten you a confirmation in five days for big parts of the past three months:

 [via https://core.jochen-hoenicke.de/queue/#3m, filter by 10-20 sats/byte]

Yet, I'm afraid that you cannot rely on getting a confirmation within five days at 10 satoshis/byte.

In the past three months, there were e.g. two weeks in August, where only a few blocks had transactions with &lt;10 sats/byte. It's very likely that you would have gone without confirmations for sixteen days. Earlier this year from early May to mid of June, you would not have gotten any confirmation at all for six weeks.

Also, please think about your users' experience. When they end up with a large number of very small unspents, it will be uneconomic for them to spend them: a big portion would get eaten up by fees, at higher fees they would be unable to make any payments at all.

Unfortunately, since the cost of transactions is in relation to the blockchain space transactions require to get confirmed, the relative cost is significantly higher for micropayments than for larger sums. I would highly recommend looking either at off-chain solutions or other blockchains.