A bull call spread has a flat floor, a slope between its strikes and a flat ceiling
Here is one diagram from the 10 Jun 2026 Nifty chain: a bull call spread, which buys a call at the strike nearest the future and sells a higher call. The horizontal axis is the index at expiry, and the vertical axis is the profit or loss in rupees on one lot of 65 units.
Step one is the flat ends. On the left both calls expire worthless, so the loss is the net premium paid and it stops growing. On the right the sold call offsets the bought one, so the profit stops growing too.
Step two is the bends. The line starts to rise at the lower strike and levels off at the upper one. The slope between them is the part of the trade that depends on the index.
Step three is the crossing with zero. That is the breakeven, and it sits above the lower strike by the net premium. The diagram is drawn at expiry, so it leaves out time value, and a position closed earlier can show a different line.
The same reading works for any combination of legs. Buying and selling the same pair give mirror diagrams, as the buying against selling question shows. The payoff builder redraws any diagram for any chain, as a teaching tool.
Before you trade. Derivatives trading carries a high risk of loss. SEBI's study "Profitability of Individual Traders in the Equity Derivatives Segment (FY25 to FY26)" (August 2026) found that 87.7% of individual traders in equity F&O made net losses in FY26, with aggregate net losses of Rs 91,685 crore. Read the SEBI study