Well it is tough to put a number, because it all depends on how much my parents need from me (they have money issues, so I help them out when they need it):
If we take this month for example
Essentials($/month):
-My rent to my parents: 300$ (saves me more than if I were in an appartment)
Electricity: 189,54$ (Sometimes I pay this part, but most of the time my parents pay the electric bill)
Groceries: 200$ (This is low, mainly because my lunch and supper are leftovers from my parents supper, the food I buy are for my breakfast, 2 snacks, fruits & Veggies, any food that has protein..yes I workout)
Bus Pass: 75,50$
Total: 765,04
My Lifestyle:
Gym Membership + Trainer: 140$ (I know this high, but that is my only luxury really)
Prescription: 47,60$
Blow Money: 200$
Total: 387,60$
Essentials (765,04$) + Lifestyle (387,60$) = 1152,64$
Which leaves me 775$ in which I invest:
Long Term: 258,33$
Mid Term: 258,33$
Short Term: 258,33$
To Eyem: the 4K$ number I came up with is when I had to pay for our roof to be repaired. That is why I chose 4K$, because my essentials are not like someone who lives in their own home, it is more to cover a large unexpected expense like the roof.