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Position size calculator
How big to make a trade so that, if your stop fills at its price, you plan to lose only what you decided to. For forex and metals, shares, spread bets and other CFDs.
We do not give financial advice, and we make no promises about returns. This calculator only does the arithmetic on the figures you enter. Read the full notice.
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
The position sizing and risk workbook is coming soon, for sizing every trade the same way.
Trading carries risk. The value of investments can go down as well as up, and you can lose money. Past or tested results are not a guide to future results. We sell software and testing only: no advice, no signals, no promise of profit. We are not authorised by the Financial Conduct Authority. Read the full notice.
Inputs never leave your browser. Nothing you type is stored or sent anywhere.
Rates and sources: Exchange rates from the European Central Bank's euro reference rates, published once a working day, for information only. They will differ from your broker's live prices, so type your platform's rate for exact figures. Every calculator is checked automatically against separately written answers before each release. Last check: 31 October 2026.
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
- Stop distance = the gap between the entry and stop prices ÷ the pip size (forex and metals) or the point size (spread bets and other CFDs); on shares it is the gap in price. Or enter the distance itself
- Value of one pip or point per unit = pip size × units per lot for forex and metals; the price move itself for shares (prices in pence are turned into pounds); your stake for a spread bet; the value of one point per contract, from your broker, for other CFDs
- Loss per unit at the stop = (stop distance + any extra distance for spread and slippage) × value of one pip or point per unit, converted to your account currency
- Position size = amount at risk ÷ loss per unit, rounded down to your smallest size step
- Reward to risk = distance to the target ÷ (distance to the stop + any extra distance)
- Margin, if you enter leverage = position value at the entry price ÷ leverage
Choose what you are trading and the instrument. For another currency pair, pick its base and quote currencies; for shares or another CFD, pick the currency it is priced in. The target is optional: leave it blank to skip the reward figures.
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, and on silver 5,000 ounces. Pip size varies by broker: on silver most count 0.01 as a pip, which is what the calculator fills in, but some use a smaller step (broker contract specifications checked 23 October 2026). On spread bets and CFDs, the point size is how far the price moves for one point, and your provider sets it. Brokers differ, so the fine-tune settings (extra distance, smallest size step, pip size, units per lot, point size and leverage) 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. When your account is in the first currency of the pair, it is converted at the stop’s price.
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.
More free tools for traders & investors: all of them in one place. Coming soon: the position sizing and risk workbook.
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