What is a stop loss?

A stop loss is an exit instruction that becomes active when a specified trigger condition is met. For an asset you already own, it usually means a conditional sell below the current market. Three numbers deserve separate boxes on your worksheet: the entry price, the stop or trigger price, and the actual average fill price. They serve different purposes.

Under the usual stop-market structure, reaching the stop activates a market order. Under stop-limit, it activates a limit order. The trigger starts the next step; it does not reserve a buyer at that price. Binance describes these as STOP_LOSS and STOP_LOSS_LIMIT in its Spot API material. Names and availability differ across products and interfaces, so verify the order description on the exact market you use. [1]

Stop Market vs Stop Limit: the practical difference

For a protective sell of an asset already held
QuestionStop MarketStop Limit
After the trigger?Market sellLimit sell
Execution price?Available bids, potentially several pricesLimit price or higher
Main trade-off?Accept an uncertain exit priceAccept possible non-execution
Can a remainder exist?Yes, depending on liquidity and venue protectionsYes, if too little demand meets the limit

A market order prioritizes immediate matching, but “market” is not a universal promise of a complete fill under every condition. Coinbase explicitly documents multiple-price fills and market-protection mechanisms that can leave a partial fill. A sell limit sets a floor for the execution price, before fees, rather than a maximum account loss. If the order remains open while the asset falls, the unsold units still carry risk. [2]

One price drop, two different outcomes

This is a hypothetical order book, not historical market data. You hold 10 units bought at $100 each. Your sell stop is $95. For the stop-limit version, your limit is $94.50 and the order remains active until canceled. After the trigger, assume the only immediately available bids are 4 units at $94 and 6 at $93.80. Assume a functioning exchange, no additional restrictions, and no fees for this first calculation.

  • Stop Market: 4 × $94 + 6 × $93.80 = $938.80 proceeds. Divide by 10 to obtain an average fill of $93.88. Against the $1,000 entry cost, the loss is $61.20.
  • Stop Limit: neither bid meets the $94.50 minimum. Nothing sells in this snapshot. You retain all 10 units and an open limit sell. A later rebound might fill it, but a continued fall might not.

The planned loss at exactly $95 was $50. The market-order example loses $11.20 more before fees. The limit-order example has no realized sale loss yet; that does not make its economic loss zero. It still holds the asset. If only 3 units later find buyers at $94.50, 7 remain exposed.

Moving the sell limit to $93.80 would make both displayed bid levels eligible in this simplified snapshot. That changes the trade-off rather than solving it: you accept a lower minimum price, and bids can still disappear before matching. No fixed gap between the stop and limit guarantees an exit.

Why your stop price differs from your fill

Slippage is the difference between an expected execution price and the actual result. A moving market and insufficient quantity at the best bid can both contribute. A seller consumes bids, not the last price printed on a chart. A chart can show $95 while the bids available to your order are lower. Spread and order-book depth therefore matter alongside the trigger. [3]

In the example, adverse slippage relative to the stop is ($95 − $93.88) ÷ $95 × 100 = about 1.18%. That is not the total trade loss, which is 6.12% of the $100 entry before fees. Keeping those denominators separate prevents a small-looking execution percentage from hiding a larger investment loss.

Our trading volume guide explains what turnover measures. A large 24-hour volume number alone cannot tell you how much demand is available at your intended exit at this instant. Likewise, a positive buy-share reading on a dashboard does not guarantee liquidity for your own order.

How to calculate position size from a loss budget

Use this arithmetic as a planning exercise, not as a recommended risk percentage. Suppose a hypothetical $1,000 account allocates a $10 loss budget to one unleveraged trade. Entry is $100 and the planned exit is $95. Before costs, the estimated quantity is:

Quantity = loss budget ÷ (entry − planned exit)
10 ÷ (100 − 95) = 2 units

Two units cost $200. The account balance is not the position value, and the $10 budget is not the amount invested. If the same two units exit at $93.88 instead, the loss becomes $12.24 before fees. A budget is a scenario assumption, not an exchange-enforced ceiling.

Now reserve a hypothetical $0.20 per unit for combined entry/exit costs and slippage. The estimate becomes 10 ÷ (5 + 0.20) = 1.923076 units. If the pair only permits steps of 0.01, rounding down gives 1.92 units, costing $192 before entry fees, and a modeled loss of $9.984. The allowance is invented for this exercise, not a fee quote or a forecast of worst-case slippage. A worse fill can exceed it.

Also cap quantity by available buying power, allow for entry fees, and check minimum order value and quantity increments. Binance publishes separate price, lot-size and notional filters; precision that looks valid in a calculator can still be rejected by a trading pair. [4]

My stop loss did not work: what to check

  1. Was it accepted? Look for an order identifier and status, not just values left in a form. Record a rejection message before changing parameters.
  2. Did the trigger occur on the configured price source? Confirm the pair and market. A screenshot from a different exchange is not evidence that this order triggered.
  3. Was it triggered but still open? A stop-limit can become a live limit without finding an eligible buyer.
  4. Was it partially filled? Read executed quantity, remaining quantity, average fill and fees. One fill notification does not prove the entire position closed.
  5. Did another action cancel or replace it? Check order history, linked orders and expiration. For OCO, one-cancels-the-other links two order legs; do not assume independent protection after the other leg changes state. [5]

A useful journal row contains: order ID, market, side, quantity, trigger source, stop, limit if applicable, status, executed quantity, average fill and fees. That record distinguishes a trigger problem from a liquidity problem. Never publish credentials or API secrets with a support screenshot.

Why futures add a separate liquidation risk

The examples above concern selling an owned asset without leverage. Futures add a liquidation mechanism. On Binance Futures, liquidation uses the mark price, while a stop can use a different selected trigger source such as the last price. The mark can reach liquidation before a last-price stop fires. Placing a stop very close to liquidation is therefore not a dependable buffer. [6]

Price-protection settings can also prevent a conditional order from triggering when the difference between mark and last price exceeds the relevant threshold. Read the contract's current rules; do not assume a feature called “protection” guarantees an earlier exit. [7] Our liquidation guide covers the broader mechanism. Margin, collateral changes and funding are outside the simple spot sizing example here.

A five-line exit plan you can actually review

Before considering a real order, complete this exercise on paper or a simulator: “I own ___ units. My trigger is ___ on ___ price source. After triggering, the order becomes ___. If only part fills, the remaining exposure is ___. I will verify completion using ___.” If any blank is unclear, the order name alone has not explained the risk.

For the ten-unit example, write down both outcomes before choosing a hypothetical order: accept a worse immediate execution price, or retain units if the minimum sell price cannot be met. Then stress the assumptions. What if the bid falls another dollar? What if only half the quantity fills? What if a fee reduces the quantity available to sell? These questions make an exit plan more useful than choosing a round percentage and calling it safe.

There is no universal stop distance that suits every asset, time horizon and market. This lesson explains order behavior and arithmetic. It does not select an entry, recommend leverage, or predict where an asset will trade.