Desk note · 12 March 2026
Write the stop distance before you write the size
A round lot feels tidy. It also hides the fact that two ideas with the same lot can risk very different money once the stop is measured.
Most students who arrive at Phra Sumen already have a size they like. Twenty contracts. A hundred shares. One standard lot. The number is familiar, so it goes on the ticket first, and the stop is nudged until the loss “looks acceptable.” That habit reverses the only order that keeps a chart honest.
Distance comes first. On a printed chart the invalidation is a price: the swing low that should not break, or the swing high the short idea cannot survive. The stop sits at that price, with a small allowance for the spread you actually pay. Only then do you know how far the idea is allowed to go against you.
Size is what remains after you divide a risk unit by that distance. If the distance is wide, the size shrinks. If the distance is tight because the structure is tight, the size may be larger — and it should be, or the tight stop was wasted. The familiar lot rarely survives this division, which is why people resist doing the division first.
A useful check on a quiet evening: take the last ten ideas you marked and write only the stop distance in price, then in baht per unit. Do not write the size you used. The column of distances will be uneven. If your sizes were even, your money at risk was not. Chart-based risk control is the decision to let that unevenness show up in the size instead of in the loss.
In the Chart Risk Studio we do not move on to size until the distance is written in both units. It feels slow on evening two. It is the whole method.
The Chart Risk Studio is where this measurement is practiced out loud. All desk notes