Who it's for — Systematic traders, scalpers, and anyone wanting to minimize the impact of Commissions (Fees) on their trading account.
Post Only is not a separate order type, but a checkbox (an option) you can tick when placing a Limit Order.
By selecting "Post Only", you are giving the exchange a very strict instruction: "Place this order ONLY if it ends up in the Order Book making me a Maker. If, due to a sudden price drop, this Limit would execute instantly like a Market order, CANCEL IT!"
In simple terms — You want to buy at $100 with a Limit order (hoping to pay base fees or even receive a small rebate from the exchange). But just as you click "Buy", the market price drops to $99$. A normal Limit order, in this case, would execute instantly at $99, effectively becoming a Market order (Taker), making you pay the high fees. If you had ticked "Post Only", the system understands the risk and simply cancels your order before executing it, saving you from unexpected fees.
Taker vs Maker (Review)
- Maker: "Makes" the market. Adds liquidity to the book. Fees are low or even negative (they pay you to trade!).
- Taker: "Takes" from the market. Removes liquidity (Market Orders). Fees are high.
When you absolutely must use it
- Scalping and High Frequency Trading: When your profit margin is tiny (e.g., 0.1%), paying a Taker Fee of 0.05% on entry and 0.05% on exit means burning your entire gain. Post Only saves your life.
- Orders placed very close to current price: If the price fluctuates wildly and is right next to your Limit, there is a huge risk the Limit "bites" the Ask and becomes a Taker. Ticking Post Only guarantees the mathematics of your business costs.
Summary Sheet
- Function: Guarantees the order adds liquidity to the book, never the opposite.
- Result: You either enter paying Maker Fees, or the order is instantly canceled (never executed as Taker).
- Platforms: Standard option on Bybit, Binance, OKX, and all major derivatives exchanges.
Links
- commissions — Why you should fight to be a Maker.
- limit-order — The base order to which Post Only is applied.
- bronze-path
Module: Module 3 — Orders and Operations
Know what happens when you click buy or sell.
