Every market has its graveyard, and the tombstones rarely say "bad strategy." They say "too big." A trader with a mediocre edge and small positions survives to improve; a trader with a decent edge and oversized positions dies in the first cold streak. Position sizing is not a detail of trading — it is the survival system.
One number decides your lifespan
Before any entry, one question outranks all others: if this trade loses, what fraction of my account goes with it? The residents' standard answer is 2% or less. Not because 2% is magic, but because of what mathematics does to losing streaks — and losing streaks are not an accident. They are a scheduled feature of any strategy with a win rate below 100%.
A 50%-win-rate strategy will produce a 7-loss streak surprisingly often over a few hundred trades. Plan for the streak, not for the average day.
The calculation: three numbers, one division
Proper sizing takes ten seconds and three inputs: account size, risk percentage, and stop distance. Multiply the first two to get your maximum loss in currency. Divide by the stop distance. The result is your position size — an output, never a choice.
Notice what this does psychologically: the trade can now do its worst and cost you exactly what you budgeted. Fear shrinks to a line item. Most "discipline problems" in trading are actually sizing problems wearing a disguise.
Why percentage risk is an automatic brake
Risking a fixed percentage (rather than a fixed amount) has a hidden gift: as you lose, your position sizes shrink automatically; as you win, they grow. The system taps the brake in drawdowns and leans on the accelerator in good runs, with no willpower required. Fixed-percentage sizing is the closest thing retail trading has to a self-driving safety system.
Risk of ruin — the number nobody computes
Combine win rate, payoff ratio and risk-per-trade and you can estimate the probability of ever hitting zero. The classical tables say what intuition won't: at 10% risk per trade, even good strategies carry a frightening chance of ruin; at 2%, the same strategies become nearly unkillable. Same edge, different bet size, opposite fates. The market did not change — the exposure did.
That is the entire philosophy of this city's guardian, Nagi: "Before you learn to win, learn not to die." Winning methods can be improved forever, but only by traders who are still here.
SUMMARY
- Decide the fraction of your account one trade may cost — 2% or less — before anything else.
- Position size = (capital × risk%) ÷ stop distance. An output, never a mood.
- Streaks are scheduled, not accidental; percentage risk shrinks your bets automatically when they arrive.
- Same edge, different sizing, opposite fates. Survival is the strategy.
Frequently asked questions
Is 2% a universal rule?
It is a widely used ceiling, not a law. Beginners and unverified strategies deserve 1% or less; a thoroughly verified method might justify slightly more. The principle is fixed: decide the fraction before the trade, and never negotiate with an open position.
What if my calculated position is smaller than the broker's minimum?
That is a signal your account is too small for that instrument or stop distance — not a reason to oversize. Use a broker with smaller minimum units, widen your timeframe, or trade less.
Does this apply to high-leverage offshore accounts?
Especially there. Leverage changes how much you CAN bet, not how much you SHOULD. The risk fraction is defined by your stop and account, and it works identically at 25x or 1000x.