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).

1. Effective stop distance: 0.0020 + 0.0001 = 0.0021.
2. Loss per micro lot: 0.0021 x 1,000 = 2.10 USD.
3. Commission per micro lot: 7.00 x (1,000 / 100,000) = 0.07 USD, so 2.17 USD per micro lot at the stop.
4. Micro lots: 100.00 / 2.17 = 46.08, rounded down to 46 micro lots = 46,000 units = 0.46 standard lots.
5. Check the worst case: 46 x 2.17 = 99.82 USD. Inside the 100.00 budget.
6. Notional value: 46,000 x 1.1000 = 50,600 USD.
7. Effective leverage: 50,600 / 10,000 = 5.06:1.

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:

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:

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

1. Decide the percentage of your balance you accept losing on this trade.
2. Decide where the trade is wrong, in price terms. This comes from your read of the chart, not from your account size.
3. Compute the units from steps 1 and 2, including the spread and the commission.
4. 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.
5. 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.

Open the position size calculator

Questions traders ask

No. Leverage decides how much margin locks up, not how large the position should be. On this page's example the size is 46 micro lots whether the cap is 1:30 or 1:500, and the loss at the stop stays 99.82 USD. Only the margin — 50,600 / 10,000 gives an effective 5.06:1 — moves.

The size stops being about risk and becomes about borrowing capacity. Sizing to the margin ceiling produces 272,000 units at 1:30, where one 21-pip move costs 571.20 USD, 5.7% of the account. Nothing about the setup changed — only the unit count did.

Yes, and the table above is the warning. At a 1:500 cap the maximum position loses 9,544.50 USD on the same 21-pip move — 95.4% of a 10,000 USD account, on a trade the broker would happily have opened. "My broker offers 500:1" describes how large a mistake you are permitted, not how good the opportunity is.

Partly. Even at a 1:30 retail cap you can still lose 5.7% of the account on one trade, which is five times a typical 1% risk. Caps limit borrowing; they do not size trades for you, and the limits differ by regulator and jurisdiction.

Size from risk first — budget and stop distance give the unit count — then check the notional against your available margin and any per-symbol limit. Margin is a constraint applied after sizing, never an input into it.

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.