📌 Key Takeaway
The only way to prevent stop-outs is to size lots by the 1% risk rule. A properly sized lot keeps your margin level around 1,000%, making it structurally impossible to be stopped out before your stop-loss is reached.
“I raised my lot size and got stopped out by the broker.” “I don’t really understand margin level.” If you don’t grasp the relationship between lot size and margin, you can be force-closed (stopped out) due to insufficient margin — even while following your money-management rules.
This article covers how to calculate required margin, how margin level and stop-out work, and their relationship to lot size. Reading Lot Calculation Basics and Why You Should Drop Fixed Lots first will deepen your understanding.
What Is Required Margin?
Required margin is the minimum collateral needed to hold a position of a given lot size. Because FX is leveraged, you hold a position by locking up a fraction of the trade value as margin — not the full amount.
Required margin = Trade size × Current price ÷ Leverage
Example: USDJPY 1 lot (100,000 units)
| Leverage | Calculation (price 150) | Required margin |
|---|---|---|
| 25x | 100k × 150 ÷ 25 | ¥600,000 |
| 100x | 100k × 150 ÷ 100 | ¥150,000 |
| 500x | 100k × 150 ÷ 500 | ¥30,000 |
At the same 1 lot, higher leverage means smaller required margin. Note that maximum leverage varies significantly by jurisdiction and broker (for example, retail leverage is capped at 25:1 in Japan, 50:1 in the US, 30:1 in the EU/UK, while some offshore brokers offer far higher). Always confirm the cap with your own broker.
Margin Level and Stop-Out
Margin level shows how much cushion your equity has against your open positions.
Margin level (%) = Equity ÷ Used margin × 100 Equity = Balance + Unrealized P&L
As unrealized losses grow, equity falls and the margin level drops. When it falls below a certain threshold, a stop-out (forced liquidation) triggers and your positions are automatically closed.
The stop-out threshold varies by broker (e.g. some trigger at 50% margin level, others at 100%, and some offshore brokers at lower levels). Always check your broker’s rules. A stop-out is a safety mechanism to halt losses before your balance goes negative — but it locks in your loss the moment it fires.
Bigger Lots → Lower Margin Level
A larger lot means more required margin, so for the same equity your initial margin level is lower and there’s less room before a stop-out. With ¥600,000 equity, USDJPY, 25x leverage:
| Lot | Required margin | Margin level at entry | Loss tolerance before stop-out (approx.) |
|---|---|---|---|
| 0.1 | ¥60,000 | 1,000% | Very large |
| 0.5 | ¥300,000 | 200% | Moderate |
| 0.9 | ¥540,000 | ~111% | Tiny |
*Margin level and tolerance are approximate and vary with price and the broker’s stop-out level. At 0.9 lots the margin level is low from the moment you enter, so a small adverse move triggers a stop-out almost immediately. A lot that’s too large for the account gets stopped out before reaching your stop-loss — the worst-case scenario.
Distinguish the Two “Lot Ceilings”
Lot size has two ceilings of different natures. Only a lot satisfying both is a “safe lot.”
- ① Margin ceiling: do you even have the required margin (can you open it)? Is the margin level high enough?
- ② Risk ceiling: is the loss at your stop within 1% of the account (the 1% rule)?
Beginners tend to size lots by ① alone (“can I open it?”), but what truly matters is ② the risk ceiling. If you size by the 1% rule, the required margin is a tiny fraction of the account and the margin level stays naturally high. In other words, satisfy ② and ① is automatically cleared.
1%-rule lots keep margin level comfortably high
For example, ¥600,000 account, 40-pip stop, 1% risk → lot ≈ 0.1 (loss ¥6,000). Required margin is about ¥60,000, putting margin level around 1,000% — stop-out is essentially a non-issue. Sizing by risk % itself protects the account on the margin side too.
Conversely, most traders who get stopped out have entered an oversized lot with no regard for risk. A falling margin level is a symptom that appears as a result of breaking your money-management rules.
Preventing Oversized Lots: Auto-Lots Calculation EA (Free)
The best way to break the oversized-lot → low-margin-level → stop-out chain is to only ever open risk-percent-appropriate lots in the first place. When entering lots manually, humans tend to slip in an oversized lot because “it looks fine.”
TraderIsMe’s Auto-Lots Calculation EA derives the right lot from the stop-loss line via “account equity × risk %”, so it physically won’t place an oversized lot that would endanger your margin level. Risk management and margin management are protected simultaneously.
For setup, see Free EAs — Common Setup Guide. For feature details, see Auto-Lots Calculation EA Manual.
Summary
- Required margin = Trade size × price ÷ leverage. Bigger lot / lower leverage → more margin needed
- Margin level = Equity ÷ Used margin × 100. Below a threshold → stop-out (forced liquidation) (threshold varies by broker)
- Bigger lots lower the initial margin level and risk getting stopped out before reaching your stop-loss
- Two lot ceilings: ① margin (can you open it?) ② risk (the 1% rule). Satisfy ② and ① is automatic
- Sizing by risk % keeps margin level naturally high. Auto-Lots Calculation EA physically prevents oversized lots
If you have to worry about margin level, that’s already a sign your lot is too big. Follow the 1% rule and your margin level stays comfortably high — stop-outs become something that simply never happens to you.
Related Articles
- Why You Should Drop Fixed Lots — Risk-Percent Position Sizing — Sizing lots that protect margin level
- The 1% Rule in FX Money Management — The Only Way Pros Stay in the Game — The risk-ceiling standard
- Lot Calculation Basics — How to Size Trades from Stop-Loss Pips — Computing the right lot
- How to Place a Stop-Loss — Setting Stops on Technical Grounds — The stop width that sets your lot
- Auto-Lots Calculation EA — Features and Input Parameters — Free EA that prevents oversized lots