The position size calculator
Luxabit's position size calculator works out how many units you can trade so that hitting your stop-loss costs exactly the risk you chose. It calculates in your browser and never sends anything to the AI.
The position size calculator turns your own risk rule into a size. You enter your account size, your risk per trade, your entry and your stop-loss; it shows how much is at risk and how many units that allows.
You find it next to the trade-plan card in the workspace. When you have recorded a trade plan, your entry and stop-loss are already filled in, and your risk per trade too if you stated it as a percentage. If you connected your exchange, your account size is filled in with the balance of your trading account there, in USD; otherwise you type it once and your browser remembers it. You can always type over it.
The calculation
- Amount at risk = account size × risk per trade ÷ 100.
- Position size (units) = amount at risk ÷ the distance between entry and stop-loss.
- Position value = position size × entry.
Example: an account of 5,000 with 1% risk puts 50 at risk. With an entry at 100 and a stop-loss at 98, the distance is 2, so the size is 50 ÷ 2 = 25 units, with a position value of 2,500. If the stop-loss is hit, you lose about 50: the 1% you chose.
Units are coins or shares, depending on the instrument. For crypto and stocks the calculator works in whatever currency your account and prices are in.
Forex, gold, indices and oil
Fill in the instrument (your trade plan's is filled in for you). When Luxabit recognises a forex pair, a metal, an index CFD or oil, the calculator also shows:
- Position size in lots: units ÷ the contract size of one lot.
- Stop distance in pips for forex pairs: one pip is 0.0001, or 0.01 for pairs quoted in JPY or HUF.
- Account currency: pick the currency your account is in. Profit and loss on these instruments is in the currency the price is quoted in (USD for EURUSD, JPY for USDJPY). When that is your account currency, or your account currency is the first one in the pair, Luxabit converts with the price itself. Otherwise, such as EURGBP on a USD account, it asks you for the exchange rate.
The contract size is filled in with the usual default, and you can type over it, because brokers differ, especially for indices and oil:
| Instrument | 1 lot | Also recognised as |
|---|---|---|
| Forex pairs, e.g. EURUSD | 100,000 units of the first currency | — |
| XAUUSD | 100 ounces | GOLD |
| XAGUSD | 5,000 ounces | SILVER |
| XPTUSD | 100 ounces | — |
| XPDUSD | 100 ounces | — |
| US30 | 1 × the index price | DJ30, DJI, WS30, USA30 |
| US100 | 1 × the index price | NAS100, USTEC, NDX, USA100 |
| US500 | 1 × the index price | SPX500, SPX, USA500 |
| GER40 | 1 × the index price | DE40, DAX40, DAX, GER30, DE30 |
| UK100 | 1 × the index price | FTSE100 |
| NL25 | 1 × the index price | AEX, NETH25 |
| JP225 | 1 × the index price | JPN225, NIKKEI |
| USOIL | 1,000 barrels | WTI, XTIUSD, CL |
| UKOIL | 1,000 barrels | BRENT, XBRUSD |
Example: a USD account of 10,000 with 1% risk puts 100 at risk. EURUSD with an entry at 1.0850 and a stop-loss at 1.0820 is 30 pips away (0.0030), so the size is 100 ÷ 0.0030 = 33,333 units, or 0.33 lots.
What it leaves out
The result is the size where the price distance to your stop costs your chosen amount. It does not include fees, funding, spread or slippage, and a stop-loss can fill at a worse price in a fast market. Check your broker's contract size and minimum order size, and what leverage means for your margin.
Your inputs stay with you
The calculator calculates in your browser. With a connected exchange, Luxabit reads your balance with your read-only key each time you open the workspace and passes it to your browser, without storing it. An account size you type is remembered only in your own browser. Neither is ever sent to the AI: the coach works in R and percent only. It is a calculator on your own inputs, not advice: you choose the account size, the risk and the levels.
Why size positions this way at all? Read Position sizing: how much to risk per trade.