Position Size Calculator
Calculate optimal lot sizes for any trade — protect your funded account with precise risk-based position sizing used by professional prop traders.
How to Use This Calculator
Select your trading style preset → Enter your account size → Adjust risk percentage → Input entry & stop loss levels → View recommended position size. The calculator shows exactly how many lots to trade while staying within safe drawdown limits.
Account Size
Trading Style
Trade Parameters
Position Size
Dollar Risk
$1,000.00
50 pips × $10/pip
Position Size
0.00 lots
20 units
Standard
0.00
Mini
0.0
Micro
0
Room for 5+ losses today (20.0% of 5% daily limit)
Risk Comparison Matrix
Same trade setup at different risk levels
0.5% risk
0.00
std lots
$500.00
10 losses till breach
1% risk
0.00
std lots
$1,000.00
5 losses till breach
1.5% risk
0.00
std lots
$1,500.00
3 losses till breach
2% risk
0.00
std lots
$2,000.00
2 losses till breach
Pro Tip: Most successful prop traders use 0.5-1% risk. At 1% risk on a $100K account, you can sustain 5 consecutive losses before hitting the 5% daily drawdown limit. Compare pass rates to understand why conservative sizing wins.
The Position Sizing Formula
Understand the math behind proper risk management
Position Size = Risk Amount ÷ (SL Distance × Pip Value)
Risk Amount
Account Balance × Risk %
$100,000 × 1% = $1,000.00
SL Distance
|Entry - Stop Loss| in pips
50 pips
Pip Value
$/pip for 1 standard lot
$10/pip
This formula ensures consistent dollar risk regardless of stop loss distance or currency pair. A wider stop loss automatically reduces your position size, keeping risk constant — essential for maintaining stable equity curves during prop firm evaluations.
Position Sizing for Prop Firm Challenges
Position sizing is the foundation of risk management in prop firm challenges. Getting it wrong is the fastest path to account termination — getting it right lets you trade with confidence, knowing exactly how much you stand to lose on any given trade. This calculator automates the process so you can focus on finding high-quality setups.
Why Fixed-Dollar Risk Matters
Instead of trading a fixed lot size, professional traders calculate position size based on the distance to their stop loss. A 10-pip scalp trade requires a much larger lot size than a 150-pip swing trade to risk the same dollar amount. This approach keeps your risk consistent across different trading strategies and timeframes, which is essential for maintaining stable equity curves during evaluations.
Common Position Sizing Mistakes
The most common mistake is using the same lot size for every trade. If you trade 1 standard lot on a 10-pip stop loss, you risk $100. But the same 1 lot on a 100-pip stop risks $1,000 — ten times more. Prop firms like FTMO and The5ers evaluate consistency, and inconsistent risk sizing creates erratic equity curves that trigger drawdown violations.
Adapting Position Size to Your Challenge
During the evaluation phase, most traders should risk 0.5-1% per trade. This provides enough margin to withstand a losing streak without breaching drawdown limits. If your challenge has aggressive profit targets (like 1-step challenges requiring 8-10%), you might increase to 1.5% per trade — but never risk more than ⅓ of your daily drawdown limit. Use our profit calculator to see if conservative sizing can still hit your target within the allowed timeframe.
Remember: the goal isn't to maximise profit per trade — it's to pass the challenge. Once funded, you can always scale up your risk within the firm's scaling plan. Compare account sizes to find the right starting point, and check challenge costs to maximise value. For help choosing the right challenge, try our risk profile matcher.