Two numbers that get confused constantly
Notional value is the full size of the position you control — one standard lot of EUR/USD at 1.0850 is 100,000 × 1.0850 = $108,500 of currency. Margin is the deposit your broker locks up to let you hold that position. Leverage is just the ratio between them.
At 50:1, one dollar of margin controls fifty dollars of notional — a 2% margin requirement. So that $108,500 position needs 108,500 ÷ 50 = $2,170 of margin. At 30:1 (the retail cap on major pairs in the UK and EU) it needs $3,617. Same position, different deposit locked.
Required margin = notional value ÷ leverage. Higher leverage simply means less of your balance is tied up per position — it says nothing about how much you make or lose when price moves.
The thing leverage does not do
Here is the misconception that costs people money: leverage does not amplify your profit per pip. Your profit and loss per pip is set entirely by position size — by how many lots you hold (see pip value). One standard lot of EUR/USD makes or loses about $10 a pip whether your account leverage is 30:1 or 500:1.
What higher leverage changes is the maximum position your balance will permit. And that is exactly the danger. Given the room to open a position 50 or 100 times the size of your equity, the temptation is to use it — and the moment you do, ordinary market noise becomes fatal.
How a 2% move wipes a fully-leveraged account
Suppose you have $2,000 of equity and you use the full 50:1 — opening a position with $100,000 of notional (50 × your equity). Your P&L now moves at 50× the percentage that price moves:
- Price moves 2% against you → you lose 2% × $100,000 = $2,000 → your entire equity.
- Price moves just 1% against you → you lose $1,000 — half the account on a move that EUR/USD can make in a quiet afternoon.
That is the whole mechanism. A 2% adverse move is unremarkable. Leveraged to the hilt, it is a wipeout. The leverage didn't lose the money — the position size the leverage allowed did.
Stop thinking "my broker gives me 50:1, so I can trade big." Start thinking "my risk per trade is 1% of equity (lesson 7-2), so the position is whatever size makes my stop cost that much — and leverage just needs to be high enough to permit that size." Leverage becomes a non-event. That is the correct relationship to it.
Margin call and stop-out: the broker's tripwires
Once a position is open, the broker watches four numbers in real time:
- Equity
- Your balance plus the floating profit or loss on open trades. This is your real, live account value.
- Used margin
- The total margin locked across all open positions.
- Free margin
- Equity − used margin. What's left to absorb drawdown or open new trades.
- Margin level
- (Equity ÷ used margin) × 100%. The health gauge the broker acts on.
As a losing trade bleeds equity, the margin level falls. Cross the broker's margin-call threshold (often 100%) and you're warned. Hit the stop-out level (often 50%) and the broker starts force-closing your positions — worst first — to stop your equity going negative. You don't get to choose which, or when. The maths decides.
Most regulated retail brokers offer negative-balance protection, so you can't lose more than your deposit. And regulators cap retail leverage — in the UK and EU, 30:1 on major pairs, lower on minors, gold, and indices. Those caps exist precisely because the arithmetic above is so reliably lethal at 200:1 or 500:1.
Try the numbers yourself
The simulator below lets you set an account size, leverage, and position size, then watch margin used, free margin, and the move it takes to hit stop-out. Push the leverage up and the stop-out distance shrinks toward nothing — which is the entire lesson in one slider.
This is Lesson 1-4 in long form
Leverage, margin, and the stop-out mechanic — with the simulator and a quiz gate at 70% — is free in the course. Series 1 is free to read; a free account unlocks all 44 lessons and saves your progress.