Leverage, Margin and Position Size
The three numbers people collapse into one
Leverage, margin and position size get used interchangeably in trading forums and they are not interchangeable. Keeping them separate removes most of the confusion people bring to this topic:
- Position size — how many units of the instrument you hold. This is the number that determines your outcome.
- Margin — the part of your balance the broker freezes as collateral while the position is open. It is a deposit, not a cost and not a loss.
- Leverage — the ratio between the notional value of the position and the money backing it. It is a description of the position after you have chosen it, not an instruction.
The useful one is effective leverage, because nobody chooses it directly. It is whatever your size produces. A trader who risks 1% of a 10,000 USD account on a 20-pip stop ends up using effective leverage somewhere around 5:1 no matter what maximum their broker advertises.
Worked example: same risk, four different leverage caps
A 10,000 USD account, risking 1% (100.00 USD), buying EUR/USD at 1.1000 with a stop 20 pips away, a 1-pip spread, commission of 7 USD per standard lot round turn, and a broker dealing in micro lots (1,000 units, or 0.01 lots).
- Effective stop distance: 0.0020 + 0.0001 = 0.0021.
- Loss per micro lot: 0.0021 x 1,000 = 2.10 USD.
- Commission per micro lot: 7.00 x (1,000 / 100,000) = 0.07 USD, so 2.17 USD per micro lot at the stop.
- Micro lots: 100.00 / 2.17 = 46.08, rounded down to 46 micro lots = 46,000 units = 0.46 standard lots.
- Check the worst case: 46 x 2.17 = 99.82 USD. Inside the 100.00 budget.
- Notional value: 46,000 x 1.1000 = 50,600 USD.
- Effective leverage: 50,600 / 10,000 = 5.06:1.
| Available leverage | Required margin | Usable? | Position size | Max loss at stop |
|---|---|---|---|---|
| 1:30 | 1,686.67 USD | yes, plenty | 0.46 lots | 99.82 USD |
| 1:50 | 1,012.00 USD | yes | 0.46 lots | 99.82 USD |
| 1:200 | 253.00 USD | yes | 0.46 lots | 99.82 USD |
| 1:500 | 101.20 USD | yes | 0.46 lots | 99.82 USD |
Every row produces the identical trade, because the size was derived from the 100.00 risk budget and the stop distance — neither of which mentions leverage. Margin changes how much of your balance is locked up; risk stays at 99.82. This is the whole point: when size comes from risk, leverage is an output.
What happens when you size from margin instead
The dangerous direction is the reverse one: letting available margin tell you how big to go. Same account, same pair, same 0.0021 stop distance, but now the trader takes the largest position the margin allows:
| Available leverage | Max notional | Units (rounded to step) | Loss if the stop is hit | Share of equity lost |
|---|---|---|---|---|
| 1:30 | 300,000 USD | 272,000 | 571.20 USD | 5.7% |
| 1:50 | 500,000 USD | 454,000 | 953.40 USD | 9.5% |
| 1:200 | 2,000,000 USD | 1,818,000 | 3,817.80 USD | 38.2% |
| 1:500 | 5,000,000 USD | 4,545,000 | 9,544.50 USD | 95.4% |
Look at the last row. One ordinary 21-pip move against you takes almost the entire account, on a trade the broker would happily have let you open. Nothing about the setup got worse; only the unit count did. This is why "my broker offers 500:1" is not a feature description, it is a statement about how large a mistake you are allowed to make.
Note also the first row: even at a 1:30 cap you can still lose 5.7% of the account on one trade. Caps limit how much you can borrow. They do not size your trades for you.
The regulatory caps are ceilings, not recommendations
Maximum leverage for retail clients is set by regulators, and the ceilings differ by jurisdiction. Published retail limits include:
| Jurisdiction | Regulator | Major currency pairs | Other pairs |
|---|---|---|---|
| United States | CFTC / NFA | 1:50 | 1:20 |
| European Union | ESMA | 1:30 | 1:20 to 1:10 |
| United Kingdom | FCA | 1:30 | 1:20 to 1:10 |
| Australia | ASIC | 1:30 | 1:20 to 1:10 |
| Japan | FSA | 1:25 | lower |
Under the ESMA and FCA regimes there are also related protections, including mandatory negative balance protection for retail clients and a margin close-out rule that forces positions shut when equity falls to 50% of the required margin. Brokers in lightly regulated jurisdictions advertise far higher ratios — 1:500 or more — precisely because no cap applies to them.
All of this concerns how much you can borrow. None of it answers how much you should risk, which stays your own decision and your own arithmetic.
The practical order of operations
- Decide the percentage of your balance you accept losing on this trade.
- Decide where the trade is wrong, in price terms. This comes from your read of the chart, not from your account size.
- Compute the units from steps 1 and 2, including the spread and the commission.
- Check the margin requirement for that unit count. If you do not have enough free margin, the size comes down — but it is the size that was too large, not the risk budget.
- Read the resulting effective leverage afterwards. If it is higher than you are comfortable with, the honest lever to turn is step 2: a wider stop with the same risk produces a smaller position, because the inverse relationship between stop distance and size works identically in every market.
A stop-out is not a pricing problem. It happens when floating loss consumes free margin, which happens when the unit count was set by margin rather than by risk.
Related guides
- How to calculate position size in forex — the four inputs and the full formula.
- Lot sizes explained — units, pip values and lot steps.
- How much should you risk per trade? — losing streaks and recovery arithmetic.
- Position sizing for prop firm evaluations — how drawdown rules interact with leverage.