How do I calculate the right position size for every trade?

In F&O: Lots = Risk Amount / (Stop in points × lot size). Always calculate before entering, never size based on how confident you feel about the trade.

Formula: Position Size = (Account × Risk %) / Stop Loss Distance. Example: ₹5L account, risk 1% = ₹5,000. Stop = 20 points. Lot size = ₹5,000 / 20 = 250 shares. Simple but most traders skip this.