Position sizing is deciding how much capital to commit to a single trade or holding. Whether a bad outcome is an inconvenience or a catastrophe is decided here, and it matters more than entry timing, which receives far more attention. An asset that can fall 80% without changing your circumstances is a different asset from the same position sized four times larger, even though the chart is identical.
Why position sizing matters more than the trade
Being right about direction is not enough.
Picking winners 60% of the time while sizing positions so that one loss wipes out ten wins loses money. Picking winners 40% of the time while sizing so that no single loss matters can come out ahead. Sizing is what converts a win rate into an outcome.
It is also the only part of a trade you fully control. Direction is a guess. On the market, entry price depends. Size is yours.
The fixed percentage approach to sizing
Most common, and simplest.
Risk a fixed percentage of total capital on each position, typically somewhere between 0.5% and 2%. The percentage refers to the amount you would lose if your stop is hit, not the amount you invest.
Here is the arithmetic. With $10,000 in capital and 1% risk per trade, the most you can lose on any single position is $100. If your entry is $50 and your stop is $45, you lose $5 per unit at the stop, so you can hold 20 units, a $1,000 position.
The position is $1,000. The risk is $100. Confusing the two is the most common sizing error.
Why risk small percentages: the drawdown arithmetic
Because of the drawdown arithmetic.
| Loss | Gain required to recover |
|---|---|
| 10% | 11% |
| 25% | 33% |
| 50% | 100% |
| 75% | 300% |
| 90% | 900% |
Ten consecutive losses at 1% each cost roughly 9.6% of capital, which recovers with an 11% gain. Ten consecutive losses at 10% each cost roughly 65%, which needs a 186% gain. Losing streaks happen to every approach. Sizing decides whether you survive them.
Volatility-adjusted sizing
Here is a refinement that accounts for how much an asset moves.
Two positions of equal dollar size in Bitcoin and in a small-cap token carry very different risk, because the token might move 20% in a day and Bitcoin 3%. Volatility-adjusted sizing scales the position so that the expected daily movement is similar across holdings.
Practically, that means holding less of what moves more. Sized this way, a portfolio looks unbalanced by dollar weight and balanced by risk contribution. Comparing Bitcoin to gold, analysts typically weight it at 0.2 to 0.3 times gold's dollar allocation to equalize risk.
Correlation: when positions move as one
Ten positions are not ten independent bets when they all fall together.
Especially under stress, crypto assets are heavily correlated. During the crash of 10 October 2025, roughly $19 billion in leveraged positions liquidated across 1.62 million accounts within hours, and almost every asset fell together. With ten altcoin positions each sized at 2% risk, a trader was not risking 2%. Closer to 20% was the real figure, because the positions moved as one.
Sizing therefore has to account for total correlated exposure, not just per-position risk.
Common sizing errors
- Sizing by conviction. Feeling certain about a trade is not a reason to size it larger. Certainty is where the largest losses come from.
- Confusing position size with risk. A $1,000 position with a stop 10% away risks $100, not $1,000. Setting size by the investment amount rather than the stop distance produces inconsistent risk.
- Adding to losers. Increasing a position as it falls raises exposure exactly when the thesis is being disproved.
- Ignoring leverage. A 2% position at 10x leverage is a 20% position.
- Sizing without a stop. If you have not decided where you are wrong, you cannot calculate what you are risking.
What position sizing does not do
- It does not pick good trades. Sizing a bad idea correctly still loses money, just less of it.
- It does not prevent losses. It bounds them.
- It does not remove tail risk. Exchange failure, exploits, and gaps past your stop all exceed the planned loss.
- It does not tell you what percentage suits you. That depends on your capital, income, horizon, and tolerance for consecutive losses, and no page can decide it.
Where mb.io fits
Market risk is what position sizing bounds. Custody risk is the other category you can directly reduce by choosing where assets sit.
mb.io is a regulated crypto spot exchange backed by MultiBank Group, a financial institution founded in 2005 that serves more than 2 million clients across 100+ countries.
- Regulated by VARA in the UAE and AUSTRAC in Australia
- 10/10 security score from Hacken, an independent blockchain security auditor
- Institutional-grade MPC custody powered by Fireblocks, with segregated client funds
- A curated list of assets, so you're not sorting through thousands of tokens to find the ones worth trading
- Buy, sell, and swap in three steps, from sign-up to purchase
- 24/7 multilingual client support
Open your account and start trading on mb.io.
Frequently asked questions
What is position sizing?
Deciding how much capital to commit to a single trade or holding. It determines whether a bad outcome is survivable, and it matters more than entry timing.
How much should I risk per trade?
Common practice is a fixed small percentage of total capital, often between 0.5% and 2%, where the percentage refers to the loss at your stop rather than the position size. What suits you depends on circumstances this page cannot assess.
What is the difference between position size and risk?
How much you invest is position size. How much you lose if your stop is hit is risk. With a stop 10% away, a $1,000 position risks $100.
Why does position sizing matter more than entry?
Because sizing converts a win rate into an outcome. A trader right 60% of the time can lose money if one loss erases ten wins. Size is also the only part of a trade you fully control.
What is volatility-adjusted sizing?
Scaling positions so that the expected daily movement is similar across holdings. It means holding less of assets that move more, so that a small-cap token and Bitcoin contribute similar risk despite different dollar weights.
How does correlation affect position sizing?
Correlated positions move together, so ten altcoins each risking 2% can behave like one position risking 20% in a crash. Sizing has to account for total correlated exposure.
Should I size bigger when I am confident?
Conviction is not information about the outcome, and the largest losses historically come from oversized positions in trades the holder felt certain about.
Does position sizing work with leverage?
The same arithmetic applies, with leverage multiplying the effective size. A 2% position at 10x leverage is a 20% position, and liquidation adds a failure mode spot holdings do not have.
