Fill probability, and the price of impatience
A limit order at the mid fills when someone on the other side thinks the mid is a good price. That is the whole mechanism. There is no queue you can join, no fill-rate table worth trusting, and the only lever you have is how far you are willing to walk toward the bid and how long you are willing to wait.
Start with what this page will not do.
The chart that does not exist
The natural thing to publish here is a curve: fill rate against distance from the mid, so you could look up that a mid order fills 40 percent of the time and a penny below fills 65 percent.
No such data exists in any form worth quoting. Brokers do not publish per-order fill statistics for options, the exchanges publish trade prints without the orders that never traded, and every percentage you will find in a forum post is somebody's recollection of their own last twenty trades on one ticker. Publishing a made-up curve would look authoritative and be worthless, so here is the arithmetic that is actually knowable instead.
What each penny is worth
CSCO April 17 $64 call, $0.58 bid at $0.66 ask. You are selling one contract against 100 shares at $58.40.
| Limit price | Credit | Against the mid | Annualized static return |
|---|---|---|---|
| $0.66, the ask | $66 | +$4 | 9.2% |
| $0.64 | $64 | +$2 | 8.9% |
| $0.62, the mid | $62 | even | 8.6% |
| $0.60 | $60 | -$2 | 8.3% |
| $0.58, the bid | $58 | -$4 | 8.1% |
One penny is one dollar per contract, and on this position it is about 0.14 points of annualized return. Walking the whole way from mid to bid costs 0.5 points a year.
That is the honest scale of the argument. Small per trade, and it is 6.5 percent of your annual income from the position, which is the framing that makes people pay attention.
What decides whether it fills
Whether the mid is actually the fair price. On a symmetric two-sided market with real competition, it usually is, and a mid order fills quickly. On a skewed market it is not. Quotes of $0.58 by $0.66 with 400 contracts bid and 3 offered are telling you where the weight is, and the fair price is nearer the bid than the middle.
Whether the market maker's model agrees with yours. They are pricing off their own volatility surface. If their model says the call is worth $0.59, no amount of patience gets you $0.62, because your order is not competitive at any speed.
Whether the underlying moves. This is the one that actually fills most resting orders. Your $0.62 offer sits unfilled for eleven minutes, CSCO ticks up 15 cents, the whole option market repositions, and your order is now inside the new spread. You did not get a better fill through skill. You got taken out by a move.
Size. One contract fills against almost anything. Twenty contracts on a chain quoting 3 up needs the market maker to want your whole order, and it will not fill at the same price a single one would.
A procedure that works
Decide the floor before you send anything. On this trade: "I will sell at $0.62, I will walk to $0.60, and below that I am not doing the trade today."
Then work it.
- Start at the mid, or a cent better if the market is wide. Give it two or three minutes. Most fills that are going to happen happen here.
- Step one penny at a time. Not two. The difference between $0.62 and $0.61 is a dollar, and the difference between $0.62 and $0.58 is four.
- Stop at your floor. The floor is the entire point of writing it down, and the moment you move it is the moment the procedure stops existing.
- Do not send a market order. On a $0.08 spread it costs $4 and on a $0.30 spread it costs $15, and the option chain is not the place to save yourself the effort of typing a price.
The mistake on the other side
Refusing to move.
A trader sits at $0.62 for four days on a contract with a fair value of $0.59, then gives up. They saved the $3 they were arguing about and gave up the entire trade, and the trade they did not put on returned nothing at all. Against $62 of premium, a $3 concession is 5 percent of the credit and 100 percent of whether the position exists.
Both errors cost the same thing, and one of them feels like discipline, which is why it is more common. Walking to the bid on every order and refusing to move a cent are the same mistake wearing different clothes.
Two conditions worth avoiding entirely
The first fifteen minutes. Option spreads at the open are wide while market makers work out where the underlying is settling. Nothing about a 45-day covered call needs to be executed at 9:31.
The last hour on expiration Friday. Liquidity in an expiring contract thins through the afternoon and the worst fills of the week print at 3:45. If you know on Thursday that you want out, get out on Friday morning.
Neither of those is about fill probability exactly. Both are about the spread being wider than usual at the moment you chose to trade, which you can simply not do.
OptionsKing scores every candidate strike on a deterministic 0 to 100 scale, blends that score with the return on the capital the trade ties up, and shows you the highest-ranked handful. There is no minimum score. How it works covers what the ranking does and does not tell you.
Questions people actually ask
Will a limit order at the mid fill?
Sometimes, and nobody can give you a reliable percentage. It fills when the other side considers the mid a fair price, which depends on where their model sits and how balanced the quote is. A market showing 400 contracts bid against 3 offered is telling you the fair price is not the middle.
How much does each penny matter on an option order?
One cent is $1 per contract. On a worked covered call that is about 0.14 points of annualized return per penny, and walking from the mid to the bid costs $4, which is 6.5 percent of the annual income from the position.
Should I use market orders on options?
No. A market order pays the whole spread, which was $4 on a tight contract in the worked example and $15 on a wide one. Options spreads are wide enough that a limit price is worth the few seconds it takes to type.
How long should I wait for an options fill?
A few minutes at each price, then step one cent, with a floor you decided before sending the order. Holding out for three extra dollars for four days and then abandoning the trade is a worse outcome than the concession you refused.
Sources
Rules and thresholds above were checked against these documents on August 4, 2026. Exchange and broker rules change. Confirm anything you are about to act on with your own broker.
Keep reading
Do the math on your own trade
Every price in this article is an illustrative worked example, not a quote. Read Screening and probability for the rest of the series, and the disclaimer before you act on any of it. Selling options carries real risk of loss, and the loss can be far larger than the premium you collected.