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Position size calculator
How big to make a trade so that, if your stop is hit, you lose only what you decided to. For forex and metals, shares, spread bets and other CFDs.
Important
We do not give financial advice, and we make no promises about returns. Our tools and calculators do not recommend trades, give signals or tell you what to buy or sell. They work only from the figures and rules you give them. We test and automate the strategy you bring us. Whether to trade it, and whatever it does in the market, is your decision and your risk.
From your broker. Often 1 for an index CFD.
Your account and risk
Your stop
Fine-tune: spread, size step, leverage
0.01 lots on most forex accounts; 1 for whole shares.
How far the price moves for one point.
Shows the margin the position would need.
Position size (lots)
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Loss if the stop is hit
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Working
A stop does not always fill at your price: gaps and slippage can make a loss bigger than planned. Nothing you type is stored or sent anywhere. Exchange rates are filled in from the European Central Bank’s euro foreign exchange reference rates (ecb.europa.eu), published once a working day, for information only. Our own server fetches them, so your browser never contacts anyone else. Rates between two currencies other than the euro are worked out by us from the euro rates. They will differ from your broker’s live prices, so type your platform’s rate for exact figures.
How it works
- Amount at risk = account size × risk %, or the fixed amount you enter
- Loss per unit at the stop = (stop distance + any extra distance) × value of one pip or point per unit
- Position size = amount at risk ÷ loss per unit, rounded down to your size step
- Reward to risk = distance to the target ÷ distance to the stop
For forex, a pip is 0.0001 on most pairs and 0.01 on yen pairs, and a lot is 100,000 units; on gold, a lot is usually 100 ounces. Brokers differ, so the fine-tune settings let you match yours. When your account currency is not the currency the instrument is priced in, the loss is converted at the exchange rate shown.
Questions
How does the calculator work out a position size?
It divides the amount you are prepared to lose by the loss each unit would make if your stop is hit. For forex that loss is the stop in pips times the value of a pip per lot; for shares it is the distance in price; for a spread bet your stake is the loss per point. The answer is then rounded down to your broker's smallest size step, so the loss at your stop is never more than you set.
Why round down instead of to the nearest size?
Rounding to the nearest lot can quietly put more at risk than you chose. Rounding down keeps the loss at your stop within your limit. The calculator also shows the exact size before rounding and what the rounded size actually risks.
Does it work for spread betting?
Yes. Choose spread betting and it gives your stake in pounds a point. Check what your provider counts as a point on each market, and set the point size to match if it is not 1.
What about UK shares priced in pence?
Most UK shares are quoted in pence. Choose the pence option and enter prices as your platform shows them; the calculator converts to pounds for you.
What does the extra distance setting do?
It adds a number of pips or points to your stop when sizing, to allow for the spread and for slippage. A stop does not always fill at your price, and gaps can make a loss larger than planned.
Where does the exchange rate come from?
When one is needed, it is filled in from the European Central Bank's daily euro reference rates, which our own server fetches, so your browser never contacts anyone else. It is a once-a-day rate, not a live price. For exact figures, type the rate from your platform.
Does this calculator tell me what to trade?
No. It does arithmetic on the figures you enter. It does not recommend trades, give signals or judge whether a position is sensible.
What this is, and what it is not
This calculator carries out the arithmetic on the figures you enter. It does not choose trades, give signals or recommend any investment, and its output is not advice. BrightDragon Systems Ltd is not authorised or regulated by the Financial Conduct Authority and does not provide regulated financial services.
Trading carries risk and you can lose money. Leveraged products such as CFDs and spread bets can lose you more than you expect, quickly. Check every figure against your own platform before you trade.
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