How to set a stop loss
Put the stop where your reason for being in the trade stops being true — beyond the swing low that defines the trend, or past the level that has held repeatedly — and then size the position so that being wrong costs the percentage of your account you decided in advance. The stop's location comes from the chart; the position size absorbs whatever that costs.
The mistake almost everyone makes first
The instinctive order is: decide how much to buy, then put a stop somewhere the loss feels survivable. That produces a stop placed by your feelings about money rather than by anything on the chart, and it sits at a price that means nothing to the market — so it gets hit by noise, repeatedly, on trades whose thesis was never actually broken.
Reverse it. The stop is a statement about the chart. The size is a statement about your account. Keeping those two decisions separate is most of what "discipline" means in practice.
What invalidation actually looks like
A stop level should correspond to a sentence you could say out loud. Some examples that pass that test:
- “I am long because lows keep rising. A close below the last low means they are not.”
- “I am long because this level has held three times. A decisive break means the buyer defending it is done.”
- “I am short a failed breakout. Reclaiming the breakout level means it was not a failure.”
And one that fails it: “I am long and I can afford to lose $200.” That is a budget, not an invalidation.
Clearing the noise
A stop exactly on the level is a stop at the most crowded price on the chart. Look at the last ten or twenty candles on your timeframe, note how far the wicks routinely extend past a level before reversing, and place the stop beyond that.
This costs you a slightly wider stop and therefore a slightly smaller position. That is the correct trade — a smaller position that survives noise beats a larger one that gets shaken out of a thesis that was right.
Then size it
Money at risk divided by distance to the stop. Risking $100 with a stop $5 away gives 20 units; move the stop to $8 away and it gives 12.5. Same risk, different size. The position size calculator does the arithmetic.
What ChartLens does with this
Every analysis includes an explicit invalidation condition, written as a sentence rather than a number — and the risk-confirm step will not let you save a trade to your record until you have ticked a box confirming you read it. That friction is intentional. It is the only moment in the flow that asks you to commit in advance, and it is the one that separates a plan from a position you will rationalise later.
People also ask
Where should a stop loss go?
Beyond the level whose break would mean your reason for entering no longer holds — under the swing low that defines the trend, or past the level that has held three times. Not at a round number, and not at whatever loss feels tolerable.
Should I use a percentage-based stop?
No. A fixed 2% stop is placed by your account, not by the chart, so it lands in a meaningless spot and gets hit by ordinary noise. Let the structure place the stop and the position size absorb the difference.
How far beyond the level should the stop sit?
Far enough that ordinary noise does not reach it. Look at the size of recent wicks on your timeframe and clear the largest of them. A stop exactly at the level is a stop at the price everyone else has chosen.
Is it ever right to move a stop?
Toward the entry, yes — trailing a stop as structure builds is normal. Away from the entry, no. Widening a stop because price is approaching it converts a defined loss into an undefined one.
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Written by The ChartLens team. Last updated .