I need to test my modpack on a server so I can invite all my friends without issue. We'll have around 15-20 or so players, maybe not all at once. The modpack is big, and uses tectonic mod for larger chunks. I want to know recommendations for what monthly plan I should use for my modded server, before I start?
#Recommended RAM for 300+ mc modpack?
mighty hearth
Your best bet to start is gonna be the 8 or 10gb option, thats what packs like ATM10 can run off of! So long as you preload chunks before the players actually hop on; it should be pretty smooth RAM side
What I did personally during the pregen phase just to be safe was every 4 hours have the chunky commands in a Scheduled Task just incase during pregen it crashed due to memory; but the task let it stay rolling 
honest nova
ok, thank you this is very helpful!
spiral robin
Also note - that isn't storage, it's RAM.
Storage is the toolbox, RAM is the workbench top.