Mechanics
What is strike price?
The fixed price at which an option lets you buy (a call) or sell (a put) the underlying stock.
Definition
The fixed price at which an option lets you buy (a call) or sell (a put) the underlying stock.
Strike price, explained
Every option has a strike — the agreed price the contract is built around. A call lets you buy the stock at the strike; a put lets you sell at it. Whether the strike sits above or below the live price is what makes the option worth something at expiration.
Where strike price shows up in a journal
A trading journal is where this stops being a definition and becomes your own number. sizeforzero computes it from the trades you import or log, alongside the rest of your analytics vocabulary, and every figure in the app carries an (i) that explains it in the same plain English you just read.