In Kucoin when you trade with a percentage and leverage you have to send the percentage multiplied by the leverage. So, your order should look like this:
Buy XBTUSDTM Q=500% L=100 A=Futures
This will open a 5% of your balance leveraged by x100.
Also remember that it is always calculated from your total balance. Not the available balance…
This is only when ordering by percetage. If you order by contracts it would be the normal quantity you want and the leverage you want. I don’t know why it’s this way, but it is the way it is.
I’m afraid the size of the contract is different for each coin. For example a contract in Bitcoin is 0.001BTC while on Ethereum it’s 0.01ETH. You have to go check it for every coin you want to trade.