How can I calculate the total cost of a trade?

You add up the purchase value, brokerage, STT, exchange transaction charges, GST, SEBI turnover fee, and stamp duty on the buy side, then do the same for brokerage, STT, exchange charges, GST, SEBI fee, and DP charges (if it’s a delivery sell) on the sell side. The net profit or loss is the sell proceeds minus all sell-side charges, minus the buy value and all buy-side charges. For a quick estimate before placing a trade, you use the broker’s brokerage calculator, which usually bakes in current STT and exchange rates. But for the actual, final number, you rely on the contract note and the ledger, since those reflect the exact executed price and quantity rather than an estimate based on what you intended to trade.