Position Size Calculator
Work out exactly how many lots to trade from your account size, risk percentage and stop-loss, across forex, gold, oil, indices and crypto, in your own account currency.
By Joey van Diest, founder and editorUpdated
Contract settings (match your broker)
- Money at risk
- -
- Units / quantity
- -
- Pip value (per lot)
- -
Why size from risk, not from gut feel
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.
The formula
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 genuinely 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.
Frequently asked questions
- What percentage of my account should I risk per trade?
- Most risk-management writing converges on 1% to 2% per trade, with 0.5% common for newer traders. The point of a fixed fraction is survival: at 1% risk, even ten straight losses draw the account down under 10%, which is recoverable. This calculator takes whatever percentage you choose; it does not recommend one.
- Why does the calculator ask for my account currency?
- Because a stop-loss is hit in the quote currency of the instrument, not necessarily in your currency. If a EUR-denominated account trades USD/JPY, the loss lands in yen and has to be converted to euros before it can be compared with your risk budget. The calculator applies a dated ECB reference rate for that conversion and lets you overwrite it with your broker’s rate.
- Why is my broker’s result slightly different?
- Three usual reasons: your broker uses a live conversion rate while this tool defaults to the daily ECB reference rate; your broker’s contract size for metals, oil, indices or crypto differs from the default here (edit it under contract settings); or your broker rounds lot sizes to its own step, typically 0.01 lots. Differences beyond that are worth querying with the broker.
- Does this work for futures contracts?
- Partially. The maths is identical, but futures have fixed exchange-defined contract sizes (a CL crude contract is 1,000 barrels, an MES contract is $5 per index point). Set the contract size field to your contract’s specification and treat "lots" as the number of contracts. A dedicated futures calculator with per-contract tick values is on the roadmap.
Method and limitations
The calculation is pure arithmetic on your inputs: risk budget = balance × risk%, loss per lot = stop distance × contract size (converted to your account currency), position = risk budget ÷ loss per lot. Nothing is estimated or modelled.
Limitations worth knowing: the result ignores spread, commission, slippage and swap, all of which add to the real cost of a losing trade, so treat it as the ceiling, not the target. Currency conversion defaults to a once-daily ECB reference rate rather than a live quote. Contract-size defaults follow common retail conventions and your broker may differ, which is why the field is editable and flagged per instrument. Brokers also round lot sizes to their own minimum step.
Data sources
- European Central Bank reference rates via Frankfurter — used only for account-currency conversion; ECB business day 2026-07-23, editable in the tool
This tool runs entirely in your browser. Nothing you enter is sent to us or stored.
For general information and education only. This is not financial advice and not a recommendation to buy or sell anything. Trading and investing carry risk, including the risk of losing more than your initial outlay. Always verify figures against your broker or the original source before acting on them.
Spotted an error? Email[email protected]and it will be corrected. Maintained byJoey van Diest.