Start with risk, not with lots
Decide how much you're prepared to lose if the stop is hit. A common choice is 1% of the account, which on $15,000 is $150. Then let the stop loss decide the lot size:
Lot size = Money at risk ÷ (Stop distance × Value of a 1-unit move per lot)
On gold, a $1 move is worth $100 per lot. With a $5 stop: 150 ÷ (5 × 100) = 0.30 lots. On EURUSD a pip is $10 per lot, so a 20-pip stop gives 150 ÷ (20 × 10) = 0.75 lots. On NAS100 with contract size 1, a point is $1 per lot, so a 50-point stop gives 3 lots.
Then check the margin rule
If your firm caps margin usage at 80%, you can have at most $12,000 of margin open on a $15,000 account. That's where leverage comes in. One lot of gold at 4,200 needs $14,000 of margin at 1:30 and $42,000 at 1:10.
| Stop distance | Lots at 1% risk ($150) | Margin usage at 1:30 | Margin usage at 1:10 |
|---|---|---|---|
| $2 | 0.75 | 70.0% | 210.0% ✗ |
| $3 | 0.50 | 46.7% | 140.0% ✗ |
| $5 | 0.30 | 28.0% | 84.0% ✗ |
| $8 | 0.18 | 16.8% | 50.4% |
| $10 | 0.15 | 14.0% | 42.0% |
Look at the tight stops. A $2 or $3 stop "allows" 0.75 or 0.50 lots by risk, but at 1:10 those sizes need more margin than the whole account. Even the ordinary $5 stop breaks an 80% rule at 1:10. With nothing else open, the most gold you can hold under 80% is 0.28 lots at 1:10 and 0.85 lots at 1:30.
EURUSD and NAS100 are much easier on margin. The 0.75 lots of EURUSD needs $2,850 at 1:30, which is 19%. The 3 lots of NAS100 needs $4,590 at 1:20, which is 30.6%.
Then check the daily loss limit
Say your firm allows a 4% daily loss, which on $15,000 is $600. Limits differ between firms and programs, and some are tighter than that, so use your own account's number. At 1% a trade, four losing trades in a row end your day. At many firms open losses count toward the limit too, so a trade that's deep in the red uses up that room before it's even closed. If you often take three or four trades a day, 0.5% to 0.75% per trade gives you more breathing space.
A trading day on a $15K account, step by step
Here's how the three limits play out over a normal day, with 1% risk per trade and a 4% daily loss limit ($600):
- First trade: gold with a $5 stop, 0.30 lots. Margin at 1:30 is 28% of the account. It's stopped out for −$150. Daily room left: $450.
- Second trade: EURUSD with a 20-pip stop, 0.75 lots. Margin 19%. It runs to 1:2 for +$300. The day is now +$150, and since the daily floor stays at $14,400 (4% below the day's starting balance), the room left is $750.
- Third idea: a gold setup that needs a $3 stop. By risk that's 0.50 lots, 47% margin at 1:30, which is fine. On an account with 1:10 gold leverage the same size would need 140%, so there you'd trade 0.28 lots at most, or skip it.
Nothing dramatic happened, and that's the point. Every trade was sized by the same rule, so no single trade could decide the day.
Quick reference at 1% risk
| Instrument | Typical stop | Lot size |
|---|---|---|
| Gold (XAUUSD) | $5 to $10 | 0.15 to 0.30 |
| EURUSD | 20 to 30 pips | 0.50 to 0.75 |
| NAS100, contract size 1 | 50 to 75 points | 2.00 to 3.00 |
These are starting points, not a recommendation. Your stop should go where the setup is proven wrong, and the lot size follows from it. If your gold leverage is 1:10, check the margin before every trade.
Can you trade 1 lot of gold on $15K?
Technically, at high leverage. At 1:100 it needs $4,200 of margin, which is 28% of the account. But a $1 move is then worth $100, so a normal $5 stop costs $500, about 3.3% of the account on one trade. At 1:30 the same lot needs $14,000 of margin, 93% of the account, which breaks an 80% rule before price even moves.
Use the prop firm lot size calculator to check risk, margin and daily loss in one go, and the XAUUSD lot size calculator for gold with today's price.