The math behind XAUUSD position sizing is straightforward once you understand the units. Most retail blowups happen because traders skip this step. Here it is properly.
Right-click XAUUSD in your market watch, choose Specification. The numbers that matter:
| Field | Typical value | What it means |
|---|---|---|
| Contract size | 100 | 1 lot = 100 troy ounces of gold |
| Profit currency | USD | P/L settles in USD |
| Tick size | 0.01 | Price moves in 1-cent increments |
| Tick value | 1.00 USD | 1 cent move = 1 USD per lot |
| Margin (typical) | 1-5% of notional | Depends on leverage offered. At 1:100 leverage, margin is 1%. At 1:500, it is 0.2%. |
From these, derive the key fact: 1 dollar of price movement (e.g. XAU moves from 2030.00 to 2031.00) = 100 USD P/L per standard lot.
Calculate position size for any trade:
Risk Amount = Account Balance × Risk Percent
Stop Distance = |Entry Price - Stop Loss Price|
Lot Size = Risk Amount / (Stop Distance × 100)The "× 100" comes from the contract size (100 oz per lot).
Round to broker minimum: probably 0.03 lots.
Traders coming from EUR/USD bring intuitions like "I usually trade 0.10 lots". Then they apply that to XAUUSD and get blown up.
Why: a 50 pip move on EUR/USD is approximately 5 USD per 0.10 lot. A 50 pip move on XAUUSD (which is 5 dollars in price) is 50 USD per 0.10 lot. Ten times larger position impact.
The pip-level math:
So per pip, the size is similar. But XAUUSD pip ranges are 5-10x bigger than EUR/USD. A "20 pip stop" on EUR/USD is 20 USD risk per 0.10 lot. A "20 dollar stop" on XAU is 200 USD risk per 0.10 lot.
Always think in dollar price movement, not "pips". Pips on XAU are a confusing unit.
Offshore brokers offer 1:500 or 1:1000 leverage on XAUUSD. This is technically legal but psychologically dangerous.
At 1:500 leverage with a 1,000 USD account:
The leverage allows the position. Position sizing is what should prevent it. Even with 1:500 available, do not size based on leverage. Size based on the math in section 2.
The intra-session volatility of XAU dictates minimum stop distances:
| Style | Realistic stop distance |
|---|---|
| Tick scalping (seconds to minutes) | 1-2 USD (often unworkable due to spread) |
| M1-M5 scalping | 3-8 USD |
| M15-H1 intraday | 10-25 USD |
| H4-D1 swing | 40-100 USD |
| Position trading | 100-300 USD |
If your "ideal" stop distance is below the realistic floor for your timeframe, your timeframe is wrong. Either trade a slower timeframe or accept the proper stop distance.
For convenience, here is the lot size for 1% risk at various account sizes and stop distances:
| Account ↓ / Stop → | 2 USD | 5 USD | 10 USD | 25 USD | 50 USD |
|---|---|---|---|---|---|
| 500 USD | 0.02 | 0.01 | 0.005 | 0.002 | 0.001 |
| 2,000 USD | 0.10 | 0.04 | 0.02 | 0.008 | 0.004 |
| 5,000 USD | 0.25 | 0.10 | 0.05 | 0.02 | 0.01 |
| 10,000 USD | 0.50 | 0.20 | 0.10 | 0.04 | 0.02 |
| 25,000 USD | 1.25 | 0.50 | 0.25 | 0.10 | 0.05 |
| 50,000 USD | 2.50 | 1.00 | 0.50 | 0.20 | 0.10 |
| 100,000 USD | 5.00 | 2.00 | 1.00 | 0.40 | 0.20 |
Note: many small-account combinations are below broker minimum (typically 0.01 lots). If the math says 0.005, you either trade 0.01 (doubling your risk) or skip the trade. Doubling risk on tight setups blows up accounts.
Single-trade sizing is only half the picture. Daily and weekly caps prevent multi-trade spirals.
These rules are mechanical. Following them is the trader's job; computing them is the trader's responsibility.
Even with proper position sizing for risk, margin usage matters.
At 1:100 leverage:
If your account is 10,000 USD and you have 1 lot open, you have used 20% of your margin on one position. Multiple positions multiply quickly.
Margin call typically triggers when free margin drops to a percentage of used margin (often 50% or 80%). Once it triggers, the broker can force-close positions, often at the worst possible price.
Keep used margin below 30-40% of your account balance, regardless of risk math, to maintain buffer against margin calls.
Technically anything above your broker's minimum deposit. Practically, 1,000 USD allows reasonable position sizing on intraday timeframes. Below 500 USD, broker minimums (0.01 lots) force you to risk too much per trade.
It does not affect the P/L per pip math (still 1 USD per cent per 0.01 lot). It does affect margin requirements at fixed leverage - higher gold prices mean higher margin per lot. Other than that, the math is the same.
Yes. Many free MQL5 indicators and standalone calculators exist. Verify the math against the formula above; some calculators have bugs around contract size.
Modest scaling makes sense. Anti-martingale (increase after winners, decrease after losers) is mathematically sound. Aggressive scaling (doubling after each winner) is gambling. Add 25% to position size after a successful 5-trade streak; halve back after any losing trade.
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