Limit order vs market order on Kalshi and Polymarket (and how to sell before a market closes)
A market order fills now at whatever the book offers; a limit order waits for your price. How each works on Kalshi and Polymarket, what they cost in fees and slippage, Polymarket’s GTC, GTD, FOK and FAK types, and how to cash out early.
Every trade on Kalshi or Polymarket is matched in an order book: a list of traders willing to buy (bids) and sell (asks) at each price. You can either take a price that is already there with a market order, or name your own price with a limit order and wait for someone to accept it. The choice changes what you pay, in fees and in price.
The order book in one minute
| Bids (buyers of "Yes") | Price | Asks (sellers of "Yes") |
|---|---|---|
| 55¢ | 1,000 contracts | |
| 53¢ | 300 contracts | |
| 52¢ | 200 contracts | |
| 400 contracts | 50¢ | |
| 900 contracts | 49¢ |
- The best ask (52¢) is the cheapest price you can buy at right now.
- The best bid (50¢) is the most you can sell for right now.
- The gap between them, 2¢, is the spread. The midpoint, 51¢, is what most sites show as the market's probability.
What a market order does
A market order fills immediately against the best prices in the book. Buy 600 contracts at market in the book above and you take:
- 200 at 52¢, 300 at 53¢ and 100 at 55¢,
- $318 for 600 contracts, an average of 53¢: a cent above the best ask and two above the midpoint.
That extra cost is slippage. On a deep market it is tiny; on a thin one it can be several cents (slippage, volume and spread explained). A market order also always pays the taker fee.
What a limit order does
A limit order says "buy up to 600 contracts at no more than 51¢". Nothing in the book is that cheap, so your order rests in the book as the new best bid and waits. It fills when a seller accepts your price, perhaps in seconds, perhaps never.
What you gain:
- A better price: you buy at 51¢ instead of an average of 53¢.
- Lower fees: on Kalshi a resting order that fills pays the maker rate, a quarter of the taker rate, where maker fees apply; on Polymarket makers pay nothing and can earn rebates (fees compared).
What you risk:
- No fill: if the price runs away from you, you miss the trade.
- Being picked off: a resting order can be hit by a trader who has just seen news you have not. Cancel or move stale orders when something happens.
Fees: taker vs maker on a 50¢ contract
| 100 contracts at 50¢ | Kalshi | Polymarket (4% category, for example) |
|---|---|---|
| Market order (taker) | $1.75 | $1.00 |
| Limit order that rests and fills (maker) | about $0.44 | $0 |
Order types on Polymarket
On Polymarket every order is technically a limit order; a "market order" is a limit order priced to fill immediately. The types:
| Type | What it does | Use it for |
|---|---|---|
| GTC (good till cancelled) | Rests until it fills or you cancel | Normal limit orders |
| GTD (good till date) | Rests until a time you set | Orders that should expire before news or a game starts |
| FOK (fill or kill) | Fills completely right away, or not at all | Market orders where a partial fill is useless |
| FAK (fill and kill) | Fills what it can right away, cancels the rest | Market orders where a partial fill is fine |
In the app, a market buy asks how many dollars to spend and a market sell asks how many shares to sell.
Order types on Kalshi
Kalshi offers market and limit orders. A market order fills straight away at the best available prices and pays the taker fee; a limit order rests at your price and pays the lower maker fee if it fills later. You can set limit orders to expire, and cancelling is free. How the rest of Kalshi works: how does Kalshi work.
How to sell before a market closes (cashing out early)
You never have to hold a contract to the end. To cash out:
- Sell at market: your contracts are sold at the best bid straight away. Quick, but you give up the spread.
- Sell with a limit order: offer your contracts at a price at or above the best bid and wait for a buyer.
- Buy the other side: on Kalshi, buying "No" when you hold "Yes" in the same market closes the position. On Polymarket, a Yes share and a No share of the same market can be merged back into $1.
There is no special cash-out fee: selling is a trade like any other, so the normal taker or maker fee applies. Holding to settlement costs no fee at all, which is one reason not to sell a near-certain winner at 98¢ unless you need the money. Locking in profit this way is the core of hedging: how to hedge a bet.
Which order should you use?
| Situation | Use |
|---|---|
| Deep market, you want in now, small size | Market order |
| Any market where you can wait | Limit order |
| Thin market, or a large order | Limit order, possibly split into pieces |
| News about to break | Cancel resting orders, or use GTD so they expire |
| Getting out fast after news | Market order (accept the slippage) |
Order types: frequently asked questions
Can you sell on Kalshi before the event ends?
Yes, at any time the market is open, with a market or limit order. You pay the trading fee on the sale; settlement itself is free.
Can you cash out early on Polymarket?
Yes. Sell your shares in the order book, or merge a Yes and a No share back into $1.
Is a limit order cheaper than a market order?
Usually, both in price (no slippage) and fees (maker rates are lower on Kalshi and zero on Polymarket). The cost is that it may not fill.
What is a good-till-date order?
A limit order that cancels itself at a time you choose, useful before scheduled news or the start of a game.
