Day trading, swing, position, which futures? All can help make the decision as to what you need, as well as spread trading, or longer term diversified trading make a difference. When I was at IB I kept $75,000 to $100,000 in my account and that was mostly for daytrading ES, NQ, RY, and occassional swing on bonds. Now I keep between $25,000, and $50000 with current broker.
This is extremely hard to say. If you start with 5 winning days in a row, you can double the value of your account. Or you can lose all your capital in a week. If you do not mind trading mini or micro contracts, you can start with $5k. If you trade most of the full commodity futures contracts, you need at least $10k for each contract. Some of the margins may have gone up more and you may need more. So to start, I'd recommend from $10k to $50k to start. You never want to be under capitalized.
Bruce Kovner took out $3K on a credit card to get started trading commodities in 1977. Find out the equivalent of $3K today and you have your answer.
5k for trading 1-3 micro's is actually pretty substantial sized account if you have an actual trading edge and plan on intra-day trading. If you're just going to throw on positions, average down, have no edge and still want to make money than you probably need 30-50k and hope we have no Covid type moves that take you out.
That is a safe amount to trade 1 mini for swinging, but for day-trading you can get away with a lot less, and it depends most severely on the instrument you are trading, as the performance bond requirements vary greatly between instruments. For example, the meats and grains have much less requirement than precious metals. There's a journal on here with a guy trading with a 300K account on the equivalent of anywhere from 1 to 6 equity minis through the micros, and has been having some rough swings. Rai27 I think is nick? Anyways, look through it.
Anyone can have successful "story" trading futures, with little capital or borrowing from credit card. The question is if this someone can successfully do this over many years. I had a 76% monthly return sometime last year on CL. If OP had such a good start, then he would be golden. But OP can certainly lost all gains and more. Futures trading is not good for everyone. I do not trade big positions with futures. The main thing is that I do not like the markets that open pretty much 24 hours/day. We need good rest.
Do they have to be commodity futures? Why not index futures. Also, you can get away with trading a far smaller amount now with micro contracts. $5,000 with a single micro ES contract cost you all of $50 on a 10 point drop. At only a $1 round trip contract fee this is very doable for a tiny account. $5,000 gives you a 1,000 point cushion to play with at only $5 a point.