Alright, I know that premium payouts are earned by the amount of total playing time from premium users, and I was wondering how many total premium hours would be needed to earn a single Robux?
It’s not based on hours it’s based on the percentage of time they spent on your game. So if they played your game 70% of the and another game 30% of the time, you’ll get 70% of the payouts while the other game gets 30%.
You could probably get 20 Robux at most from someone playing for a single hour however you probably will receive 3 to 10 Robux usually.
So how much robux is 100%?
So if I spent all day in a single game with premium payouts, I would 100%?
You would get ATLEAST 72 robux if 1 player spends 24h in your game.
So in theory, if you had premium you can join your own game slock the server & get some payouts?? 
Not really, it only works for other people from what i know. You cannot join on your own account and get inf payouts + it’s not worth it for your internet as you would lose like 90% of what you spend on wifi.
Why slock? and yeah, if you have two accounts, one with premium
whats the total payout if they play your game 100%
internet is sold on a flat rate 90% of the time, you get infinite internet and you pay a specific amount
Electricity is still a factor, you’d also need to DevEx at $3.50/1k.
Assuming your computer takes about 50W to stay on, and you leave your PC on 24 hours a day, that’s about 8kWh per week.
Assuming you’re in the UK, electricity comes out to around £0.24 or $0.31/kWh
Assuming you’re in the UK, your average unlimited broadband/internet is going to set you back about £24.99 a month or $31.86
Assuming that @TraderOfDominus is correct with 72 Robux per 1 player spending 24 hours in your game, you’d be making around 2232 Robux per month if it’s a 31 day month
So your income comes in at around $7.81 or £6.12, your expenses (including internet, electricity and the cost of Premium on Roblox) come out to $9.91 (electricity) + $5 (Premium) + $31.86 (internet) = $46.77 a month
That’s excluding any sort of DevEx fees or the FX fees that may proceed from DevEx’ing
good lord i love numbers
what if i run it at $0.087/kWh for 12 hours a day, free internet and 45W
had a friend trying this 1 time, 17h together gave him around 1k robux
(even tho this kinda sounds to much so maybe it were a few more hours)
Unfortunately, this document is only available internally. I’m not the only one that has been pushing for transparency inside the company, many others do as well. But since this information is already public (elsewhere), you earn 21 Robux a day for the unofficial official answer. 
But… this daily rolling amount over 30 days is split between the games the player is playing via time in game session. Not only that, there is a limit of time per game so if Player A spends at least 8 hours in Game A, they will earn 21 Robux next month, but if the same Player A spends 8 hours in your Game A, then switches to Game B and spends the rest of the 16 hours in Game B, it won’t be split, instead Game B will get all the Robux instead because one game can over-ride another for premium session time.
And this has already been complained about before here, a lot, because of AFK games eating everyone else’s premium pay. 