Once a pattern breaks, where do you get out? The classical answer is the measured move: take the height of the pattern and project that same distance from the breakout point.
How the projection works
For a head and shoulders, measure from the top of the head down to the neckline, then subtract that distance from the neckline break. For a double bottom, measure from the lows up to the neckline and add it to the breakout. For a flag, the usual convention is that the advance after the break roughly matches the length of the pole.
It is easy to apply and it gives you a number, which is why it is popular.
Why it is only an estimate
There is no mechanism that makes price travel exactly one pattern height. The projection is a convention that arose from observation, and observations vary enormously. Measured targets are reached maybe half the time in practice; the rest of the time price falls short or runs far past.
Treat the projection as one consideration among several, not as a level the market owes you. It is a reasonable place to take partial profit and move your stop, not a reason to hold a losing position that has already invalidated.
Better ways to pick an exit
- Prior levels. The next obvious support or resistance above or below is a far more reliable magnet than a projected distance.
- A multiple of risk. If you risked 40 pips, taking profit at 80 is a clean, repeatable rule that does not depend on the pattern at all.
- Trailing. For the slow patterns especially — rounding bases, long rectangles — trailing behind swing points beats any fixed target.
Scaling out
The pragmatic answer most experienced pattern traders land on: take some off at the measured move, take some at the next structural level, and let the rest run with a trailing stop. That accepts that you cannot know, and it stops the target question from being a bet.
How to check this yourself
For every pattern trade you take on a demo account, record the measured target and then record what actually happened: reached, exceeded, or fell short. After thirty trades you will have your own hit rate for projections on your instruments and timeframe — which is worth far more than the textbook claim.