Lots, Leverage and Margin

Position size decides how much an account gains or loses when the market moves. Leverage and margin are the credit-and-collateral language around that size. They are easy to misunderstand. This lesson explains the mechanics carefully and does not recommend a personal leverage setting. Hypothetical figures are classroom arithmetic only.

Position size

Position size is how much of the instrument you are long or short. In retail forex and metals, size is often described in lots. Size is the volume of economic exposure. Two traders can be “right” on direction and have completely different outcomes if one is holding a much larger position.

A useful beginner question is not “what is the maximum I can open?” It is “how much does this position make or lose if price moves against me by an amount I can actually imagine happening?”

Lots and contract size

A lot is a packaged quantity. In many forex textbooks a “standard lot” of a currency pair is 100,000 units of base currency, with mini and micro lots as fractions of that. Metals and some CFD symbols use different contract definitions. Some brokers also offer “micro” gold lots that are a fraction of a troy ounce.

Contract size is not universal. The same XAU/USD label on two platforms can represent different ounces per lot. Symbol suffixes, account types and product documents matter. Before you size a trade, read the specification for that symbol at that firm: contract size, tick value, trading hours, and margin requirement. Guessing from a blog post is how people mis-scale risk.

Leverage

Leverage lets you control a position whose notional value is larger than the cash you set aside as margin. If a firm offers 1:100 leverage, the headline meaning is that a relatively small margin can support a much larger notional position — subject to the firm’s rules and to the market not moving against you.

Leverage magnifies both gains and losses. A 1% adverse move on an unleveraged cash purchase of an asset is a 1% loss on that cash. The same 1% move on a heavily leveraged position can be a large fraction of the posted margin, or more. Leverage is not a skill. It is a multiplier on the P/L of whatever size you chose.

Margin and free margin

Margin is collateral locked to support open positions. It is not a fee you “spend” like a commission, though you can lose more than you hoped if positions go badly. Free margin is, in typical platform language, what remains of equity after used margin: a rough buffer for new trades or for existing trades moving against you.

When floating losses reduce equity, free margin shrinks. If it shrinks far enough, the firm’s risk engine may restrict new trades or begin closing positions. Exact thresholds differ by broker and account.

Hypothetical example

Imagine, as an example only, an account of 2,000 units of account currency. A position whose notional value is 20,000 uses 10:1 effective leverage on that notional, regardless of the marketing maximum on the website. A 2% adverse move on 20,000 is 400 units — already 20% of the account — before costs. The same 2% on a much smaller notional would be a much smaller dent. The market move did not change. The size did.

Maximum advertised leverage is a ceiling the firm might allow, not a target. Using all of it because it is available is a common beginner error. Availability is not suitability. This site does not tell you a “correct” leverage number for your situation.

Margin call and forced closure, at a high level

If losses reduce equity toward the firm’s maintenance threshold, you may receive a margin call warning, or the platform may simply start closing positions (stop-out) according to its rules. Forced closure is a protective process for the firm’s credit risk. It is not designed to get you a thoughtful exit. It can happen quickly in a volatile market, and the fill prices can be worse than the level you last saw.

The practical lesson is to size so that ordinary swings do not put the account at the mercy of an automatic closer. Survival is a risk-management topic; the next lessons return to stops and to planning. Leverage is the amplifier that makes those topics urgent.