An call option's Value at expiry is the amount the underlying stock price exceeds the strike price. The Profit at expiry is the value, less the premium initially paid for the option.

Value = stock price - strike

Profit = (value at expiry - option cost) × (number of contracts × 100)
_______= ((stock price - strike) - option cost)
_________× (number of contracts × 100)

The Breakeven at expiry will always be higher than the underlying stock price at the time of purchase and is the strike plus the option price.

Breakeven price = strike + option cost

To calculate profit prior to expiry requires more advanced modelling.

The price corresponds primarily to the probability of the stock closing above the strike price at expiry. This can be generalized to both call and put options having higher extrinsic* premium for strikes closer to the current stock price, longer-dated expiries, and higher stock volatility.

Profit = ((stock price - strike price) - option cost + time value)
Profit = × (100 × number of contracts)

*extrinsic premium is any cost above the intrinsic value

You can use our calculator above, which uses the Black Scholes formula to estimate the value of a long call purchase before or at expiry.

Related: What happens when options expire to ensure you capture the maximum profit

There is no cap on the maximum possible profit using a long call strategy, and profit increases linearly with the rising price of the underlying stock. Loss is generally limited to the initial value of the option paid.