How to Calculate Position Size in Forex — The Complete Guide

Position sizing is the most important risk management skill in forex. Get it wrong, and you'll blow up your account. Get it right, and you'll survive losing streaks and build wealth over time.

The Position Size Formula

The professional forex position sizing formula is:

Position Size (Lots) = (Account Size × Risk % × Exchange Rate) / (Stop Loss Pips × Pip Value)

Let's break this down with a real example.

Real-World Example: Calculating Position Size

• **Account Size:** $10,000
• **Risk per Trade:** 1% (this is the professional standard)
• **Currency Pair:** EUR/USD (trading euro against dollar)
• **Entry:** 1.0800
• **Stop Loss:** 1.0700 (100 pips away)
• **Pip Value (1 lot EUR/USD):** $10

Using the formula:

**Risk Amount** = $10,000 × 1% = $100 (maximum you'll lose if stopped out)

**Position Size** = $100 / (100 pips × $10 per pip) = 0.1 lots (10,000 units)

Why 1% Risk per Trade?

Professional traders risk 1% per trade because it allows you to survive losing streaks. Even with a 50% win rate, you'll eventually hit a run of 5-10 consecutive losses. At 1% risk, a 10-trade losing streak only reduces your account by 9.5% (compound effect), which is recoverable.

Use the BrokersDB Position Size Calculator

Don't calculate manually every time. Use our free Position Size Calculator to instantly calculate perfect position sizes.

Common Position Sizing Mistakes

• ❌ **Risking more than 1% per trade:** "This trade looks like a sure winner" — every trader thinks this before a 200-pip move against them
• ❌ **Not using a stop loss:** Positions without stops are position-sizing disasters
• ❌ **Using leverage incorrectly:** 50:1 leverage at 5% risk is suicidal — one bad trade wipes you out
• ❌ **Ignoring pip value differences:** GBP/USD pip value is $10, but USD/JPY is $9.50 — it matters for large accounts

The Bottom Line

Master position sizing before you trade one real pip. This single skill will determine whether you're a trader who loses money, breaks even, or builds long-term wealth.