how to calculate a number of message sent per day for lorawan in different SF12, …SF7 and different packet size ?
You need to use the Semtech ‘LoRa Calculator’ tool. Not sure where it can be downloaded these days, Semtech seem to move it around.
This website does a reasonable on-line job, it seems to agree with the Semtech tool when I tried it.
Most of the LoRaWAN\TTN defaults are listed, so you need to supply the spreading factor used and the packet payload length in bytes. This will give you the on-air time in mS.
Fair use limit is 30 seconds of air time per day.
Cant see how it follows on as such, transmission of pictures via TTN is not going to be pratical in a free to use system, but to calculate air time you can follow this advice;
Although a 10 bytes of data you want will grow a bit by the time the addressing info is added, maybe by an extra 14 bytes or so.