Why is position size important?
“How far should I go in?” is more important than “Which direction should I go in?”**
Even if you are 80% correct in the direction, there are many cases where a 20% large loss due to the wrong position size will wipe out all 80% of the small profit. The biggest difference between a professional trader and an amateur is not the ability to predict direction but the ability to manage money.
Core principle: 1 transaction risk = 1-2% of account
Account $5,000
Risk 1% → Maximum allowable loss per time = $50
Risk 2% → Maximum allowable loss per time = $100
Outside these numbers:
- One large loss erases dozens of small profits
- Leads to emotional trading (revenge trading)
- Accounts are depleted quickly
Position size calculation formula
Basic formula
Position size = Allowable loss amount / Stop loss distance
Allowable loss amount = account balance × risk %
Stop Loss Distance = |Entry Price - Stop Loss| / Entry price (%)
Practical example 1 (BTC long)
Account: $10,000
Risk: 1% = $100
Entry price: $95,000
Stop loss: $93,500 (down 1.58%)
Position size = $100 / 1.58% = $6,329
Without leverage: Buy $6,329 worth of BTC
3x leverage: $2,110 margin × 3x = $6,330 position
Practical example 2 (ETH short)
Account: $8,000
Risk: 1.5% = $120
Entry price: $3,400
Stop Loss: $3,500 (2.94% above)
Position size = $120 / 2.94% = $4,082
5x leverage: $816 margin × 5x = $4,080 position
🔢 Calculate automatically with Position Size Calculator.
Automatic determination of leverage according to stop loss distance
Many traders make the mistake of setting up leverage first. Correct approach:
Leverage is determined by stop loss distance (%)
Based on 1% risk of the account:
- Stop loss 0.5% → Leverage up to 200x (theoretical)
- Stop loss 1% → Leverage up to 100x
- Stop loss 2% → Leverage up to 50x
- Stop loss 5% → Leverage up to 20x
- Stop loss 10% → Leverage up to 10x
Realistic use: Use only 50-70% of theoretical maximum leverage
Position size when entering split
The total risk should remain the same when entering in installments rather than all at once.
Goal: 1% of account = $100 risk
Split Entry Plan:
- 1st entry: 50% ($50 risk) → Entry price $95,000, Stop loss $93,500
- 2nd entry: 30% ($30 risk) → Additional entry after confirmation of rebound
- 3rd entry: 20% ($20 risk) → After confirmation of additional increase
Total Risk: $100 (1% of account)
Appropriate risk for each account size
| Account size | Risk % | Maximum loss per session | Reason |
|---|---|---|---|
| Under $500 | 2~3% | $10~15 | It's a small amount so it's a bit flexible |
| $1,000~$5,000 | 1-2% | $10~100 | standard |
| $5,000~$20,000 | 1% | $50~200 | conservative |
| $20,000+ | 0.5~1% | $100~200 | Large accounts are more cautious |
Top 3 position sizing mistakes
Mistake 1: Sizing your bets based on your mood
“This deal is sure!” → 3 times the usual amount → If you are wrong, your account will be hit hard. The more confident you are, the smaller the size.
Mistake 2: Increasing size for recovery purposes after loss
Consecutive losses → “Let’s make up for it by doubling this time.” → Martingale strategy, 99% bankrupt in the long run
Mistake 3: Unprincipled additional entry in the profit zone
“You already have a profit, so you can add more” → Entry into greed → When the trend reverses, profit = 0, principal is damaged.
Related guides
- Position size calculator →
- Liquidation price calculator →
- Leverage risk management →
- ATR-based stop loss settings →