Why Some Option Chains Have $1 Strikes and Others Have $10
The grid isn't the same width everywhere
Pull up a chain on a $12 stock and you'll see strikes stacked every $0.50 or $1. Pull one up on a $650 stock and the rows jump by $10 or more. That's not a data glitch and it's not the broker choosing arbitrarily — it's a listing rule. Exchanges decide, in advance, how far apart strikes are allowed to be for a given underlying, based mostly on where the stock is trading. The interval determines how finely you can express a view, which is exactly why it's worth understanding before you assume every chain gives you the same precision.
The standard interval schedule
For standard equity options, the default schedule is tiered off the underlying's price: roughly $2.50 apart for stocks trading under $25, $5 apart from $25 up to $200, and $10 apart above $200. A $18 stock lists strikes at $17.50, $20, $22.50. A $90 stock lists them at $85, $90, $95. A $600 stock lists them at $590, $600, $610. The logic is proportional, not absolute — a $10 gap on a $600 stock is roughly the same percentage move as a $2.50 gap on a $150 stock. Exchanges also add strikes as the stock moves, keeping a band of listed strikes centered loosely around the current price rather than fixing them once at listing and leaving them static forever.
Why liquid names get finer strikes anyway
If the standard schedule were the whole story, a $400 stock could never trade in $1 increments. In practice, many of the most actively traded names do — because exchanges run separate programs layered on top of the default rule. A "$1 strike" program lets qualifying, high-volume underlyings list tighter increments regardless of price. A "mini-strike" or "$0.50 strike" program does the same thing for a narrow band of strikes clustered right around the current stock price, even while strikes further out-of-the-money on the same expiration stay on the wider standard spacing. That's why it's common to see $0.50 or $1 gaps near the money on a popular name, with the increments widening out to $5 or $10 as you scroll toward the edges of the same chain.
Weekly expirations tend to get this fine-strike treatment more consistently than far-dated monthlies, since weeklies are traded almost entirely by people transacting close to the current price rather than building long-term directional positions. For more on how weeklies, monthlies, and LEAPS differ beyond just strike spacing, see reading the expiration tabs on an option chain.
New strikes get added as the stock moves
Strike listing isn't a one-time event at IPO or at the start of an expiration cycle. As a stock trends, exchanges add new strikes on the far side of the move so there's always a band of reasonably-spaced choices near the current price — the reason a stock that's rallied 40% this year still has plenty of strikes above the old highs, not just a gap where the chain used to end. This also means a chain you looked at a month ago on the same underlying isn't necessarily the same chain today; strikes that were "new" then may now be deep in-the-money or deep out-of-the-money, and fresh ones will have been listed closer to the current price in the meantime.
Why the spacing actually matters to you
Wider strike spacing means fewer available deltas to choose from — on a $10-interval name you might jump from roughly 0.45 delta to 0.30 delta with no strike in between, while a $1-interval name lets you dial in almost any exposure you want. It also changes spread construction: the minimum width of a vertical or the smallest step in an iron condor is set by the interval, not by your preference, which directly affects the credit-to-width ratio and the capital a spread ties up. If you're deciding which row to trade rather than just how the grid is spaced, the mechanics of that choice are covered in choosing a strike in the option chain, and a full column-by-column breakdown of what else is on the row lives in the option chain columns most traders skip past. OptionScope's option chain view shows the actual listed strikes for whatever underlying and expiration you're on, so the spacing you're planning around is the spacing that's really there.