The short answer
A stop loss is a resting order that closes a trade at your maximum acceptable loss. Place it where your trade idea is proven wrong — beyond the structure that matters — not at a round dollar figure. The distance to that level then sizes your position, so risk is fixed before you enter. The two rules that matter most: every trade has a stop set at entry, and you never move it further away.
Why every trade needs a stop
Without a stop, a losing trade has no defined end — it can grow until it threatens the account. A stop converts an open-ended risk into a known, capped number, which is the precondition for everything else: sizing, risk-reward and expectancy all assume a fixed 1R loss.
A trade without a predefined stop is not a trade; it is an open-ended bet on being right. The stop is what makes the whole risk framework possible.
Where to place a stop
The stop belongs at the price where your reason for the trade no longer holds — the point of invalidation. For a long off a support zone, that is a decisive close below the zone. If price gets there, you were wrong, and you want to be out cheaply.
Crucially, you place the stop at the level first, then size the position so that the distance equals your chosen risk. You never pick a comfortable dollar amount and jam the stop at that distance regardless of the chart.
Structural stops
The most robust method is structural: put the stop just beyond the swing high/low or level that defines your idea. Give it a small buffer past the wicks so ordinary noise does not clip you, but keep it at the point where the setup genuinely fails.
Structural stops respect how the market actually moves. They are placed by the chart, not by your comfort, which is exactly why they work.
ATR and volatility stops
Markets breathe differently at different times, so a fixed 20-pip stop is too tight in a volatile session and too loose in a quiet one. The Average True Range (ATR) measures recent volatility, letting you set a stop a multiple of ATR away — wider when the market is moving, tighter when it is calm.
Volatility-based stops adapt to conditions and reduce the chance of being stopped by normal movement. They pair well with structure: use the structural level, and let ATR sanity-check the distance.
The mistakes that ruin accounts
Three habits do most of the damage:
- Moving the stop away to avoid a loss. This turns a 1R loss into a 3R disaster and breaks your entire expectancy. The stop moves toward profit, never away.
- Stops too tight, placed for comfort inside the noise, so good ideas get clipped before they work.
- No stop at all, or a mental stop that is quietly ignored in the moment. If it is not resting in the market, it does not exist.
Trailing stops and moving to breakeven
Once a trade moves in your favour you can trail the stop behind structure to lock in gains, or move it to breakeven to remove risk. Both are legitimate — but only in the profitable direction, and ideally by rule rather than by feeling.
Beware moving to breakeven too early: do it the moment price ticks up and you will be stopped out of winners by noise. Trail against real structure, not against every small pullback.
Frequently Asked Questions
Where should I place my stop loss?
At the price where your trade idea is invalidated — just beyond the structure or level that defines the setup, with a small buffer past the wicks. Place the stop at the level first, then size the position to that distance.
How do I size a trade from my stop?
Decide the money you will risk (for example 1% of the account), measure the stop distance in pips, and choose the lot size so that distance equals your risk. The stop distance is what sizes the position.
What is an ATR stop loss?
A stop placed a multiple of the Average True Range away from entry. Because ATR measures recent volatility, the stop widens when the market is moving and tightens when it is calm, adapting to conditions.
Should I move my stop loss?
Only toward profit — trailing behind structure or moving to breakeven. Never move a stop further away to avoid a loss; that turns a controlled 1R loss into a much larger one and destroys your expectancy.
Is a mental stop loss okay?
No. A stop that is not resting in the market is easy to ignore in the moment a trade goes against you, which is exactly when discipline fails. Place a real stop order at entry.