Skip to main content

​
Placing an Order

1

Browse markets

From the home screen, browse the list of available markets.
2

Open a market

Tap any market to open it.
3

Choose a side

Select Yes if you think the event will happen or No if you think it will not.
4

Enter amount

Enter the dollar amount you want to trade or tap Max to use your available balance.
5

Confirm order

Review your order details, then swipe up to confirm.
6

View Portfolio

Open the Portfolio tab to track your position and market value.
Positions update in real time as market prices change. You can cash out anytime while the market is open or hold until it resolves.

​
Order Types

On Polymarket US, all orders are processed as marketable limit orders.
  1. When you place an order, it executes at the best available price shown on the screen.
  2. If enough size is available at that price, your entire order is filled.
  3. If there isn’t enough size, you receive a partial fill.
  4. The unfilled portion stays on the order book as an open order until it is filled or canceled.
Execution is always based on available liquidity and standard time-and-price priority within the central limit order book (CLOB). Key points:
  • Price protection: Your order will never be filled at a worse price than the one you set.
  • Partial fills: Only available size is filled. Any remaining portion stays on the book as an open order.
  • Priority: Orders match using standard time-and-price priority within the CLOB.

​
Spreads

Every market has two prices:
  • The bid is the highest price buyers are willing to pay
  • The ask is the lowest price sellers are willing to accept
The spread is the gap between these two prices. When you buy, you pay the ask price. When you sell, you receive the bid price. Tighter spreads mean better execution; wider spreads mean higher trading cost. More liquid markets usually have tighter spreads.

​
Whole Contracts

Polymarket US does not support fractional contracts. All trades are executed in whole event contracts. When you buy using a dollar amount, the system purchases as many whole contracts as that amount can buy at the current market price. Any remaining amount that is not enough to buy a full contract returns to your cash balance. Example: You want to spend 100 dollars to buy Yes contracts priced at $0.65:
  • Each contract costs $0.65
  • 100 ÷ 0.65 = 153.84 contracts
  • You receive 153 whole contracts for $99.45
  • The remaining $0.55 returns instantly to your cash balance

​
Odds Display

1

Open odds settings

From the home screen, tap the Odds icon at the top right.
2

Choose display format

Select price (¢), percent chance (%), or American odds (+/−) from the odds menu.
3

View updated odds

Your selected display format applies across all markets.
Display TypeExample
PriceWAS 17¢ / KC 86¢
Percent chanceWAS 17% / KC 86%
American oddsWAS +488 / KC -615
All display formats show the same market information — only the way it’s shown changes.

​
Price Slippage

Price slippage occurs when the price you expect to sell at is different from the price your order actually receives. This usually happens when liquidity is low or when an outcome appears nearly decided. Why it happens:
  1. Event contracts remain open until the final outcome is confirmed, even if the result looks certain.
  2. Liquidity thins on the side that is already priced as the likely winner.
  3. With limited liquidity, your sell order may fill at lower levels than the displayed price.
For example, if a contract is trading near 97¢ close to resolution, limited demand could cause your order to fill at 94¢ instead of the expected 97¢.
Best practices:
  • Consider holding until settlement — when liquidity is thin, holding through resolution may provide better value, since winning contracts settle at full price.
  • Always check before selling — compare your position value and the current trading price to understand what you may receive if you exit early.