Position size calculator
Work out how many lots to trade so that a stop-loss hit costs the amount you chose. It runs in your browser and nothing is stored.
Your numbers
Fill in the boxes. The answer updates as you type.
The money in your trading account right now.
What you are prepared to lose if the trade goes wrong. Many traders keep this to 1% of the account or less.
The distance, in , between where you enter and where you will cut the loss.
Your answer
Trade 0.20 lots of EUR/USD. If the price moves 50 pips against you and your stop-loss is hit, you lose about $100.00 (1% of your $10,000.00 account).
Rounded down to 0.01 lot. The exact answer is 0.2 lots.
- Amount you are risking
- $100.00
- Loss if the stop is hit
- $100.00
- Trade size in units
- 20,000 units
- Value of one pip (1 lot)
- $10.00
+Show the working
- Amount you are willing to lose = $10,000.00 × 1% = $100.00.
- One pip on one standard lot of EUR/USD = 100,000 units × 0.0001 = 10 USD.
- Lots = amount at risk ÷ (stop in pips × pip value of one lot) = 100 ÷ (50 × 10) = 0.2 lots.
- Brokers sell lots in steps of 0.01, so the size is rounded down to 0.20 lots. If the stop is hit you lose 0.20 × 50 × 10 = $100.00.
EUR/USD live price
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For information only, not financial advice. Trading carries a high risk of loss. Results depend on the values you enter and on your broker's contract specifications. Risk disclosure
What is position size?
Position size is how big a trade is, usually written in lots. A standard lot is 100,000 units of the base currency, a mini lot is 10,000 and a micro lot is 1,000. The same price move makes or loses a different amount of money depending on the size, so choosing the size is how a trader controls how much a single trade can cost.
A position size calculator turns three decisions into a lot size: how much you are willing to lose, how far away your stop loss is, and what one pip is worth for the pair you trade.
The formula
- Risk amount = account balance × risk percentage ÷ 100 (or a fixed amount you type in).
- Position size in lots = risk amount ÷ (stop loss in pips × pip value of one lot).
The pip value of one lot depends on the pair and on your account currency. The calculator works it out for you in the same way as the pip value calculator on this site.
Worked examples
- EUR/USD, USD account of $10,000, risk 1%, stop 50 pips: the risk is $100. One pip for one lot is $10, so the size is 100 ÷ (50 × 10) = 0.20 lots, or 20,000 units.
- USD/JPY at 150, same account and risk, stop 25 pips: one pip for one lot is 1,000 yen ÷ 150 = about $6.67, so the size is 100 ÷ (25 × 6.67) = 0.60 lots.
- A stop of 33 pips on EUR/USD gives 100 ÷ 330 = 0.303 lots. It is rounded down to 0.30 lots, so a stop-out costs $99 instead of $100.
Why the stop loss matters
A wider stop means a smaller position for the same amount of risk. If you double the stop distance, the lot size is halved. That is why the stop should come from the trade itself (where the idea is proved wrong) and the size follows from it, not the other way round.
Limits to keep in mind
- A stop order is not a guarantee. A stop can fill at a worse price when the market jumps, so the real loss can be larger than the risk amount.
- Spreads, commissions and swap charges are costs on top of the stop distance.
- Brokers differ in lot step, minimum and maximum size, and in how they define a pip for metals and other instruments. Check your broker's contract specification.
- Margin is separate from risk. A position needs enough free margin to be opened, whatever the stop distance is.
Frequently asked questions
+How do I calculate position size in forex?
Decide the amount you are willing to lose, then divide it by your stop loss in pips multiplied by the pip value of one lot. With $100 at risk, a 50 pip stop and $10 per pip per lot, the position is 100 ÷ (50 × 10) = 0.2 lots.
+What percentage of my account should I risk per trade?
There is no correct figure and this site cannot advise you. Many traders choose a small fixed percentage of the balance, often between 0.5% and 2%, so that a run of losses does not do serious damage. Pick a number you have thought through for your own situation.
+Why is the lot size rounded down?
Most brokers only accept sizes in steps of 0.01 lot. Rounding down keeps the loss at or below the amount you chose, while rounding up would risk slightly more. The result shows the exact answer and the loss at the rounded size.
+Does this guarantee that I will lose no more than my risk amount?
No. It assumes your stop is filled at the price you set. In fast markets, over weekends or around news, a stop can be filled at a worse price (slippage), which makes the real loss larger. Spreads and commissions also add to the cost.
+What stop loss should I enter?
Enter the distance in pips between your entry price and your stop-loss price. If you do not know the distance, subtract the two prices and divide by the pip size: 0.0001 for most pairs, 0.01 for yen pairs.