To calculate lot size on gold you need three numbers: how much money you’re prepared to lose, how many dollars from your entry the stop sits, and your broker’s contract size, usually 100 ounces per lot. The formula is lots = money at risk ÷ (stop distance in USD × contract size). With 100 ounces, 1 lot makes or loses $100 for every $1 gold moves, and 0.01 lots, $1. Then round down to your broker’s volume step and check that the margin fits.
What is a lot in gold trading (XAU/USD), and where do you find yours in MT5?
A lot is the unit that measures the size of a trade. On gold, one lot usually equals 100 troy ounces, but each broker sets its own contract size, so check yours before you run any numbers.
The Specification window in MetaTrader 5
Open Market Watch (View → Market Watch; Ctrl+M on Windows), right-click the gold symbol (XAUUSD, or whatever name your broker uses, sometimes with a suffix) and choose Specification. Four lines in that window matter for lot size:
- Contract size. How many ounces there are in 1 lot.
- Minimal volume. The smallest lot your broker accepts, usually 0.01.
- Volume step. The increment by which the lot size can change. With a 0.01 step, 0.03 is valid but 0.035 isn’t.
- Digits. The number of decimals in the price. On gold it’s usually 2 or 3.
Labels vary slightly between MT5 versions. If a figure here doesn’t match your Specification window, yours is the one that counts.
Standard, mini and micro lots
With 100 ounces per lot, the usual names are:
| Size | Ounces | Per $1 gold move |
|---|---|---|
| Standard lot (1.00) | 100 | $100 |
| Mini lot (0.10) | 10 | $10 |
| Micro lot (0.01) | 1 | $1 |
Every gold lot size calculator rests on that table: ounces controlled × dollars moved. When two calculators disagree, they’re usually assuming a different contract size or a different pip.
What each gold move is worth: dollars, points and pips
What you make or lose is the ounces you control multiplied by the dollars the price moves. Buy 0.05 lots (5 ounces) at $4,000 and, if gold rises to $4,012, you make 5 × 12 = $60; if it falls to $3,992, you lose 5 × 8 = $40. The $4,000 is just a round figure; gold can move tens of dollars in a single session, as we explain in how to trade gold (XAU/USD).
Why it’s better to measure gold moves in dollars, not pips
A point is the smallest change the price can make, and it depends on your broker’s decimals: with 2 (4,000.25) it’s $0.01; with 3 (4,000.253), $0.001. So “20 points” means $0.20 on one account and $0.02 on another.
Pips are worse. In forex the convention is settled, but on gold each broker or platform defines a pip its own way (most often $0.01 or $0.10). A “50-pip stop” could be $0.50 or $5: ten times as much.
The fix is to express distances in dollars: “a stop $15 from the entry” means the same thing on any account.
Accounts in euros or pounds: MT5 converts the dollar result at the current rate, so turn your money at risk into dollars (multiply by EUR/USD or GBP/USD) before using the formula.
How to calculate lot size for XAU/USD from your risk: the formula
You don’t size a trade from what you hope to make, but from the loss you’re willing to take if the stop is hit:
lots = money at risk ÷ (stop distance in USD × contract size). With 100 ounces per lot, the divisor is the stop distance multiplied by 100.
Money at risk is usually set as a percentage of the balance. The 1% and 1.5% below are only there for the arithmetic; they’re not a recommendation.
Example 1: a $5,000 account with a $10 stop
You’re willing to lose 1%: $50. The stop is $10 from the entry and the contract is 100 ounces. Lots = 50 ÷ (10 × 100) = 0.05, which fits a 0.01 step, so you open 0.05 lots. If the stop is hit, you lose 0.05 × 100 × 10 = $50, plus the spread and any slippage.
Example 2: a $3,000 account with an $18 stop
You’re willing to lose 1.5%: $45. Lots = 45 ÷ (18 × 100) = 0.025. Your broker won’t accept that volume: with a 0.01 step, you have to choose between 0.02 and 0.03.
Round down. With 0.02 lots you risk 0.02 × 100 × 18 = $36, or 1.2% of the account. With 0.03 it would be $54, or 1.8%: 50% more, and above what you were willing to lose.
A stop doesn’t guarantee your exit price: with gaps or slippage you can lose more, as we explain in stop loss, take profit and break-even. For how the stop relates to the target, see win rate and risk-reward ratio.
Margin and the minimum lot: the two limits on your position size
The formula tells you which lot size fits your risk. Before you open the trade, check two limits that are outside your control.
The margin the position ties up
Margin is the money the broker sets aside as collateral while the trade is open. For retail clients, leverage on gold CFDs is capped at 1:20 in the EU (the limit ESMA introduced in 2018, now applied by national regulators) and in the UK under the FCA’s rules; your broker may offer less, and elsewhere it depends on the regulator and the broker. At 1:20, in simplified form:
margin = lots × contract size × price ÷ 20
With the 0.05 lots from the first example and gold at $4,000: 0.05 × 100 × 4,000 ÷ 20 = $1,000. The broker ties up 20% of the $5,000 account, even though the trade only risks $50.
Margin isn’t money lost; it’s a deposit you get back when you close. You’ll see the real figure in the Trade tab of the Toolbox (View → Toolbox), under “Margin” and “Free margin”. What happens when free margin runs short is in our guide to gold leverage.
The minimum lot and the volume step on small accounts
You can’t trade below the minimum volume, usually 0.01 lots. With a $20 stop, that micro lot risks $20 whatever you do: 2% of a $1,000 account, 4% of a $500 one. The step also means you adjust in jumps: going from 0.01 to 0.02 doubles the risk. On small accounts, the real risk tends to end up higher than planned. How much capital makes sense is covered in how much money you need for automated trading.
Fixed or balance-based lot size
Working out the lot once and leaving it fixed is convenient, but it stops adding up as soon as the balance moves. With the same $10 stop, 0.05 lots always risk $50; what changes is how much that $50 means to your account:
| Balance | Fixed 0.05 lots | Balance-based lot |
|---|---|---|
| $3,000 | $50 (1.67%) | 0.03: $30 (1%) |
| $5,000 | $50 (1%) | 0.05: $50 (1%) |
| $10,000 | $50 (0.5%) | 0.10: $100 (1%) |
With a fixed lot, each trade carries more weight as the account shrinks, just when it hurts most, and less as it grows. Sizing to the balance means recalculating the lot before every trade from the balance at that moment so that, for the same stop distance, each trade’s weight stays steady, within the limits of the broker’s minimum lot and step. To measure losing streaks, read what drawdown is.
How AUREUM handles it
With AUREUM you don’t have to calculate the lot. As the FAQ on our home page explains, it uses a reference lot mode: 0.01 lots per 1,000 of your account balance, rounded to the step your broker allows, with a minimum (your broker’s minimum lot) and a cap of 1 lot. With 5,000, it trades 0.05 lots; if the balance grows or drops, the size adapts on the next trade. The installation guide adds two examples: with 1,000, 0.01; with 500, also 0.01, because it never goes below the broker’s minimum lot.
That mode sizes the trade from what’s in the account, not from a risk percentage. If it matches the “Balance-based lot” column and Example 1, that’s pure arithmetic: the stop distances in our examples are made up and don’t describe where AUREUM places its stops or how much it risks per trade, which also depends on that distance. According to the guide, every trade has its stop loss and take profit on the broker’s server.
If you’d rather set it yourself, there’s a manual mode with the lot size you choose. The guide warns that in this mode you can pick a lot that’s too big for your capital; without enough free margin, MT5 rejects the order with a “Not enough money” error.
Common mistakes when calculating gold lot size
- Confusing lots and ounces. With a 100-ounce contract, 0.01 lots is one ounce and 1 lot is 100 ounces: mix them up and your position is a hundred times bigger or smaller than you think.
- Ignoring the volume step. An order for 0.025 lots is rejected as an invalid volume, and rounding up by eye means risking more than you calculated.
- Carrying over pips from another market. On EUR/USD a pip is 0.0001 and, with a standard lot of 100,000 euros, it’s worth $10. That habit doesn’t transfer to gold: with 100 ounces, every dollar of movement is $100 per lot.
- Forgetting the exchange rate. On a euro or pound account, plugging your risk into the formula as if it were dollars throws the lot off by the exchange rate: with EUR/USD at 1.10, by about 10%.
- Letting leverage set the size. Free margin for 0.30 lots says nothing about whether 0.30 lots fits your risk: leverage decides how much margin the broker ties up, not what you lose per dollar.
- Watching the risk and forgetting the margin. A position can respect your percentage and still not fit in your free margin, especially with several trades open.
In short: check your symbol’s Specification window, express the stop in dollars, apply the formula, round down to the volume step and check the margin before you open the trade.
The figures in this article are examples for learning the math: the gold price, exchange rates and your broker’s contract size will differ. A stop doesn’t guarantee your exit price, and gaps or slippage can make you lose more than calculated. Leveraged gold trading carries a high level of risk and you can lose the capital you deposit. The AUREUM figures we quote come from a simulation (backtest), not a live account. This content is educational and is not financial advice.
AUREUM: the lot size adjusts to your account on its own
Software that trades XAU/USD in your own MetaTrader 5 account, on the 1-hour chart. Its reference lot mode uses 0.01 lots per 1,000 of balance, with your broker’s minimum and a cap of 1 lot. Its 2020–2026 backtest is published with its drawdowns: a maximum drawdown of 21.84% across 439 trades. It’s a simulation, not a live account.
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