Position Size Calculator

Position sizing answers the only question you fully control before a trade: how much you lose if you are wrong. Fix that number first, as a percentage of the account, and the lot size falls out of the arithmetic. Sized this way, a wide stop automatically means a smaller position and a tight stop a larger one, so every trade risks the same fraction of the account regardless of the instrument or timeframe.

The alternative, picking a lot size first and hoping the stop is survivable, is how accounts die: the same 1.00 lot that is conservative on EUR/USD is wildly aggressive on gold, because contract sizes and volatility differ by an order of magnitude between instruments.

lots = (balance × risk%) ÷ (stop distance × contract size × conversion rate)

where stop distance is in price units (pips × pip size, or |entry − stop|), contract size is the units per 1.00 lot, and conversion rate turns the instrument's quote currency into your account currency (it is 1 when they already match).

A worked example

A $10,000 account risks 1% on EUR/USD with a 20-pip stop. Risk budget: $100. One standard lot is 100,000 EUR, and a pip is 0.0001, so a 20-pip stop on one lot loses 20 × 0.0001 × 100,000 = $200. The quote currency is already USD, so no conversion:

lots = $100 ÷ $200 = 0.50 lots (50,000 EUR)

Same account, same 1%, but on gold with a $5.00 stop: one lot is 100 oz, so the stop on one lot loses 5.00 × 100 = $500, and the position is $100 ÷ $500 = 0.20 lots. Same risk, very different lot number, which is the entire point.

Where other calculators go wrong

The classic failure is assuming every instrument works like forex. Index CFDs are the minefield: depending on the broker, one NAS100 lot can be worth $1, $5, $10 or $20 per point, a 20x spread in outcomes from identical inputs. Oil splits between 100-barrel CFD lots and 1,000-barrel futures. This calculator ships sensible defaults, flags every instrument where brokers differ, and lets you set the exact contract size from your broker's specification, because a position-size tool that guesses silently is worse than none.

The reason a single tool can size a EUR/USD trade, a gold trade, a Bitcoin trade and a DAX trade is that only one number changes between them: the contract size, the units one lot controls. The risk maths is identical. Pick the instrument and the calculator loads the convention most brokers use, 100,000 units for a standard forex lot, 100 ounces for gold, one coin for spot crypto, one index unit for a cash index, and you confirm or overwrite it against your broker’s specification. Everything downstream, the pip or point value and the final lot number, follows from that one field.

What trips people up is that the answer arrives in a different unit per market, and the word “lots” quietly shifts meaning. On forex it is lots of 100,000. On gold it is lots of 100 ounces. On spot crypto most people size in coins or dollars rather than lots, so set the contract size to 1 and read the result as the number of BTC or ETH. On futures, one “lot” is one exchange-defined contract, an MES or an MNQ, with a fixed multiplier per point. The calculator sizes all four; you only have to know which unit you are reading.

Sizing the stop from ATR

Many traders set the stop a multiple of Average True Range (ATR) from entry rather than a round number, so the stop scales to current volatility. That needs no separate calculator: read the instrument’s ATR off your chart, multiply by your chosen factor (1.5x and 2x are common), and enter the result as the stop distance here. A wider ATR then produces a smaller position on its own, which is exactly the behaviour you want, a volatile market gets less size for the same account risk. The formula is indifferent to how you arrived at the stop distance; ATR just decides the number you type in.