Position Size Calculator

Position sizing is the process of determining how large a position to take on any given trade. While entry and exit signals determine the direction and timing of trades, position sizing determines how much capital is at risk and, ultimately, how much you can gain or lose.

Many traders focus the majority of their energy on finding good entries. However, two traders can take the same entry on the same asset and have dramatically different outcomes based solely on how they sized their positions. Proper position sizing is what keeps a losing streak from becoming a catastrophic drawdown.

The core principle is simple: risk a fixed, predetermined percentage of your account on each trade. This percentage does not change based on conviction, recent performance, or market conditions. Consistency in risk sizing allows the law of large numbers to work in your favor over many trades.

This approach has several important properties:

• Your account can never be wiped out in a single trade
• Larger accounts automatically take larger positions, growing proportionally
• Drawdowns are limited to a predictable percentage of peak equity
• The approach scales naturally across all market conditions

The calculation follows four sequential steps. Each step depends on the previous, and every input must be determined before entering the trade.

Step 1: Risk Amount = Account Balance x Risk Percentage

Step 2: Stop Distance = |Entry Price - Stop Loss Price|

Step 3: Position Size (units) = Risk Amount / Stop Distance

Step 4: Position Size (notional) = Position Size x Entry Price

This formula ensures that if the market moves from your entry to your stop loss, you lose exactly your predefined risk amount, regardless of how wide or narrow the stop is. A wider stop will result in fewer units purchased; a tighter stop will result in more units, keeping the dollar risk constant.

Notice that your position size is determined by the stop distance, not by an arbitrary capital allocation. This is the key insight that separates systematic risk management from casual trading.

Industry convention groups traders into tiers based on how much they risk per trade. These guidelines have emerged from decades of professional trading experience.

The position sizing formula is the same for both futures and spot markets. The critical difference is that futures allow leverage, which affects the margin required but not the underlying position size calculation.

A common misconception is that using 10x leverage means you should take a 10x larger position. This is incorrect and extremely dangerous. Leverage affects only how much collateral (margin) you must post, not the risk management calculation.

Margin Required = Position Notional / Leverage

Consider this example: your formula says to buy 0.01 BTC. In spot, you post $950 in capital. In futures at 10x, you post $95 in margin. The position size is identical in both cases. The difference is that futures allows you to control the same amount of BTC with less upfront capital.

However, leverage introduces liquidation risk. If the market moves against you by more than 1/leverage before hitting your stop, you will be liquidated rather than stopped out. This is why it is critical to ensure your stop loss is always closer than your liquidation price, which the position size calculator warns you about explicitly.

• Higher leverage reduces margin but does not increase your risk amount
• Your stop loss must remain within the liquidation buffer
• Tighter stops allow higher leverage without increasing liquidation risk
• Wider stops at high leverage often push the liquidation price inside the stop

Risking 2% per trade sounds conservative until you realize that five simultaneous trades at 2% each puts 10% of your account at risk at once. If those five positions are in correlated assets, a single market event could trigger all five stop losses simultaneously.

This is the distinction between trade level risk (risk per individual position) and account level risk (total open risk across the portfolio).

Professional traders track both metrics. Common guidelines include:

• Maximum total open risk: 6% to 10% of account across all positions
• Treat correlated positions as a single combined risk unit
• BTC, ETH, and altcoins are often highly correlated; three positions may effectively be one directional bet
• Reduce individual position size when adding correlated trades

Correlation awareness is especially important in crypto markets, where most assets move together during major market events. A well diversified portfolio in traditional markets may behave like a single concentrated position in crypto during periods of market stress.

The following worked examples demonstrate the formula applied to real trading scenarios.

Risk Amount = $10,000 x 1% = $100
Stop Distance = |$95,000 - $93,000| = $2,000
Position Size = $100 / $2,000 = 0.05 BTC
Notional Value = 0.05 x $95,000 = $4,750

If stopped out: lose $100 (1% of account)

Risk Amount = $5,000 x 2% = $100
Stop Distance = |$3,500 - $3,600| = $100
Position Size = $100 / $100 = 1.0 ETH
Notional Value = 1.0 x $3,500 = $3,500
Margin Required = $3,500 / 10 = $350

If stopped out: lose $100 (2% of account)
Margin posted: $350 (7% of account)