What risk-reward ratio should I target once size is set?
Size caps what you lose, not what you should expect to win. If you're risking $10 to enter, a 1:1 target only breaks even at a 50% win rate after fees. Most traders aim for at least 2:1 so a sub-50% win rate can still be profitable. Check a specific trade with the risk/reward ratio calculator before sizing it.
Does leverage change the position size this calculator gives me?
No — size comes only from account, risk%, entry and stop. Leverage just determines how much margin you post for that same notional: a $500 position is $500 whether you post $500 at 1x or $50 at 10x, so the dollar risk is identical either way. What leverage changes is your liquidation distance, not your risk — check that separately with the 清算計算機 so a normal stop doesn't sit past your liquidation price.