Forex Position Size Calculator
Calculate forex position size based on account balance, risk percentage, and stop loss in pips. Includes Kelly criterion, risk/reward ratio, margin required, and multi-pair portfolio risk.
$
%
Position Size (Units)
—
Standard Lots —
Mini Lots —
Dollar Risk —
Pip Value at This Size —
Extended More scenarios, charts & detailed breakdown ▾
$
%
Units
—
Standard Lots —
Max Risk ($) —
Pip Value —
Professional Full parameters & maximum detail ▾
$
%
%
Position Sizing
Recommended Position Size (Units) —
Standard Lots —
Risk Amount ($) —
Reward Amount ($) —
Risk/Reward
Risk/Reward Ratio —
Margin Required —
Advanced Metrics
Kelly Criterion Size (%) —
Expected Value per Trade ($) —
How to Use This Calculator
- Enter your Account Balance.
- Set your Risk Per Trade % — 1-2% is standard for professional traders.
- Enter your Stop Loss in Pips — the maximum loss if the trade hits your stop.
- Select the Currency Pair and enter the current Exchange Rate.
- See the recommended position size in units and lots. Use Professional for Kelly criterion and margin.
Formula
Risk $ = Account Balance × Risk %
Position Size = Risk $ / (Stop Loss Pips × Pip Value per Unit)
Kelly % = Win Rate − (1 − Win Rate) / Reward:Risk Ratio
Example
Example: $10,000 account, 1% risk, 20-pip stop, EUR/USD. Risk = $100. Pip value per unit = $0.0001. Units = $100 / (20 × $0.0001) = 50,000 units (0.5 lots). At 50% win rate with 2:1 RR, Kelly = 25%, Expected Value = +$50/trade.
Frequently Asked Questions
- Position Size = (Account Balance × Risk %) / (Stop Loss Pips × Pip Value per Unit). For a $10,000 account risking 1% ($100) with a 20-pip stop on EUR/USD: $100 / (20 × $0.0001) = 50,000 units (0.5 standard lots).
- The 1% rule means you risk no more than 1% of your account on any single trade. On a $10,000 account, max risk per trade = $100. This limits drawdown and allows recovery from losing streaks.
- Kelly Criterion suggests the optimal bet size = (Win Rate - Loss Rate / Reward:Risk Ratio). In practice, traders use half-Kelly (½ of the Kelly %) to reduce volatility. Kelly > 0 means the trade has positive expected value.
- Leverage amplifies both gains and losses. A 50:1 leverage means a $1,000 margin controls $50,000 in currency. Position sizing should be based on your risk tolerance, not maximum leverage available — overleveraging is the #1 cause of blown accounts.
- Expected Value = (Win Rate × Average Win) − (Loss Rate × Average Loss). A positive EV trade is profitable over many repetitions. EV > $0 per trade is the threshold for a sustainable trading strategy.
Related Calculators
Sources & References (5) ▾
- BabyPips — Position Sizing — BabyPips
- Van Tharp — Position Sizing Strategies — Van Tharp Institute
- OANDA Risk Management Guide — OANDA
- MyFXBook Position Size Calculator — MyFXBook
- Investopedia — Forex Position Sizing — Investopedia