The Formula
Position Size = (Account Balance × Risk %) / (Entry Price - Stop Loss Price)
Step-by-Step Example
Account: $5,000
Risk per trade: 1% = $50
Entry: $65,000 (BTC long)
Stop-loss: $63,500 (2.3% below entry)
Risk per coin: $65,000 - $63,500 = $1,500
Position size: $50 / $1,500 = 0.033 BTC = ~$2,145
At 10x leverage: $214.50 margin needed
Risk-Reward Ratio
If your take-profit is $68,000 (3,000 gain) and stop-loss is $63,500 ($1,500 loss), your R:R is 2:1. Minimum acceptable R:R for any trade should be 1.5:1. With 2:1 R:R, you only need to win 34% of trades to break even.
Common Mistakes
- Risking 5-10% per trade (1-2% maximum)
- Not adjusting position size for volatility
- Using same lot size regardless of stop distance
- Ignoring fees in the calculation
- Adding to losing positions (averaging down)
For platform-specific position sizing, see leverage guide. For automated position management, see grid trading.
Why Position Sizing Matters More Than Anything Else
You can have a 70% win rate strategy and still go bankrupt if your position sizes are wrong. A single oversized loss can wipe out months of gains. Position sizing is the difference between professional traders who survive for decades and amateurs who blow their accounts in weeks.
The math is simple but ruthless: a 50% loss requires a 100% gain to recover. A 90% loss requires a 900% gain. Once you lose 50%+ of your account, the probability of recovery drops dramatically. This is why the 1% rule exists — capping risk per trade ensures no single loss can meaningfully damage your account.
The Position Size Formula
Position Size = (Account Balance x Risk Per Trade) / Stop-Loss Distance
Let us work through three examples at different account sizes:
Example 1: $1,000 Account
| Parameter | Value |
|---|---|
| Account balance | $1,000 |
| Risk per trade (1%) | $10 |
| Entry price (BTC) | $65,000 |
| Stop-loss | $63,700 (2% below entry) |
| Position size | $10 / 2% = $500 |
| Leverage needed | $500 / $1,000 = 0.5x (none needed) |
Example 2: $5,000 Account
| Parameter | Value |
|---|---|
| Account balance | $5,000 |
| Risk per trade (1%) | $50 |
| Entry price (ETH) | $3,200 |
| Stop-loss | $3,104 (3% below entry) |
| Position size | $50 / 3% = $1,667 |
| Leverage needed | $1,667 / $5,000 = 0.33x (none needed) |
Example 3: $10,000 Account, Tighter Stop
| Parameter | Value |
|---|---|
| Account balance | $10,000 |
| Risk per trade (2%) | $200 |
| Entry price (SOL) | $150 |
| Stop-loss | $147 (2% below entry) |
| Position size | $200 / 2% = $10,000 |
| Leverage needed | $10,000 / $10,000 = 1x (none needed) |
Notice: even with a $10,000 account and 2% risk, you often do not need leverage for proper position sizing. Leverage becomes necessary only when you want a larger position than your account can cover at 1x — and if you need leverage, keep it under 5x for swing trades and under 10x for day trades.
Risk Per Trade: How to Choose
| Account Size | Recommended Risk | Max Concurrent Trades | Max Portfolio Risk |
|---|---|---|---|
| Under $1,000 | 2-3% | 2-3 | 6-9% |
| $1,000-$10,000 | 1-2% | 3-5 | 5-10% |
| $10,000-$50,000 | 0.5-1% | 5-8 | 4-8% |
| Above $50,000 | 0.25-0.5% | 5-10 | 2.5-5% |
Smaller accounts can afford slightly higher risk per trade (2-3%) because the absolute dollar amount is small and you need meaningful position sizes to overcome trading fees. Larger accounts should reduce risk per trade because the absolute dollar amounts are significant.
Stop-Loss Placement: Common Methods
Technical Stop-Loss (Best Method)
Place your stop-loss below the nearest significant support level (for longs) or above resistance (for shorts). If support is at $63,000 and current price is $65,000, your stop-loss at $62,800 gives the level room to hold while protecting you if it breaks.
Percentage-Based Stop-Loss
Fixed percentage from entry: 2% for BTC, 3-5% for altcoins, 1% for scalps. Simple but does not account for market structure. Only use this if you cannot identify clear technical levels.
ATR-Based Stop-Loss (Advanced)
ATR (Average True Range) measures typical price movement over a period. Set your stop-loss at 1.5-2x ATR below your entry. This automatically adjusts for current volatility — wider stops in volatile markets, tighter stops in calm markets.
Position Size Calculator Tools
| Tool | Platform | Features | Cost |
|---|---|---|---|
| Bybit built-in calculator | Bybit futures | P&L, margin, liquidation | Free |
| OKX built-in calculator | OKX futures | Position size, margin, ROI | Free |
| TradingView position tool | Any chart | Visual risk/reward on chart | Free |
| Coinglass calculator | Web | Cross-exchange, detailed | Free |
The Risk of Ruin Table
This table shows the probability of account blowup based on win rate and risk per trade:
| Win Rate | 1% Risk Per Trade | 2% Risk Per Trade | 5% Risk Per Trade | 10% Risk Per Trade |
|---|---|---|---|---|
| 40% | 0.1% ruin risk | 2% ruin risk | 25% ruin risk | 80% ruin risk |
| 50% | ~0% | 0.5% | 12% | 50% |
| 60% | ~0% | ~0% | 2% | 20% |
Even with a 60% win rate (very good), risking 10% per trade gives you a 20% chance of blowing your account. At 1% risk per trade, the probability of ruin is essentially zero for any reasonable win rate. This is why professional traders obsess over position sizing.
Frequently Asked Questions
Should I risk the same percentage on every trade?
Yes, for consistency. Some traders use a tiered system: 1% for standard setups, 2% for high-conviction setups. But never exceed your maximum. Consistency is what makes position sizing work — one impulsive oversized trade can undo months of disciplined trading.
How do I size positions for altcoins vs BTC?
Use wider stop-losses for altcoins (3-5% vs 2% for BTC) because they are more volatile. This naturally results in smaller position sizes for the same dollar risk, which is correct — you should have smaller positions in higher-volatility assets.
What if my position size is too small to be meaningful?
If the calculated position is under $50, the trade is probably not worth taking (fees will eat your profit). Either: increase your risk per trade (up to 3% for accounts under $1,000), use a lower-fee exchange (MEXC at 0% maker), or skip that particular trade setup.