Forex Position Size Calculator
Work out how many units or lots to trade so a stop-loss at your chosen price costs a fixed percentage of your account.
Position size is the link between the risk you are willing to take on a trade and the number of units you actually buy or sell. A forex position size calculator settles that link arithmetically: fix the risk first, and the size follows with no judgement left in the final step.
Formula: units = (balance × risk%) ÷ (stop in pips × pip value per unit)
Your figures
Choose Custom to enter your broker's own pip size and contract size.
Your total account equity.
Percentage of the balance to risk if the stop is hit.
Rate to convert the pair's quote currency into your account currency. Enter 1 if they are the same.
Price increment of one pip. Only used when Instrument is Custom.
Units of the base asset in one lot. Only used when Instrument is Custom.
Results
Position size
0.50 lots
50,000 units of EUR
- Amount at risk
- US$100.00
- Stop-loss distance
- 20.0 pips
- Pip value (per standard lot)
- US$10.00
- Standard lots (100,000 units)
- 0.50
- Mini lots (10,000 units)
- 5.00
- Micro lots (1,000 units)
- 50.00
- Notional size in EUR
- 50,000
What this means
At 0.50 lots, a 20.0-pip move against a long EUR/USD position costs US$100.00 — the amount you chose to risk. This is a sizing calculation only; it says nothing about whether the trade will reach the stop or the target.
- Assumes the stop fills at exactly the stop price. Slippage, gaps and commission increase the realised loss.
- Pip size for EUR/USD is 0.0001.
Position size: 0.50 lots
The link reopens this calculator with the same numbers. Nothing you enter is sent to a server.
Continue with these figures
About the Forex Position Size calculation
This calculator estimates how many lots to trade from four inputs: your account balance, the percentage of it you are prepared to lose on the trade, and the entry and stop-loss prices. It converts the price distance into pips, works out what a pip is worth for the pair you are trading, and divides your risk budget by the two.
The relationship that matters is inverse: the tighter the stop, the larger the position needed to lose the same amount of money. A 10-pip stop produces a position five times larger than a 50-pip stop at identical risk. That is why fx position sizing has to be recalculated per trade rather than fixed once.
Forex Position Size formula
risk amount = account balance × (risk % ÷ 100)
stop in pips = |entry − stop| ÷ pip size
pip value/unit = pip size × quote-to-account rate
units = risk amount ÷ (stop in pips × pip value/unit)
lots = units ÷ 100,000- pip size
- 0.0001 for most pairs; 0.01 for pairs quoted in Japanese yen.
- quote-to-account rate
- The rate converting the pair's quote currency into your account currency. 1 when they match.
- units
- Units of the base currency — the first currency in the pair.
- lot
- 100,000 units. A mini lot is 10,000; a micro lot is 1,000.
The calculation runs in the currency the price is quoted in, then converts once at the end. A EUR/USD position produces profit and loss in US dollars regardless of what your account is denominated in, so the pip value is computed in dollars first and converted afterwards.
Dividing the risk budget by the total pip risk gives the size at which a stop-out costs exactly that budget. Everything else in the result — notional value, lot breakdown — is that number expressed in different units.
Forex Position Size: a worked example
A $10,000 account risking 1% per trade, going long EUR/USD at 1.1050 with a stop at 1.1030, with the account denominated in US dollars so the conversion rate is 1.
- Risk amount10,000 × 1% = 100
- Stop distance1.1050 − 1.1030 = 0.0020
- Stop in pips0.0020 ÷ 0.0001 = 20 pips
- Pip value per unit0.0001 × 1 = 0.0001
- Units100 ÷ (20 × 0.0001) = 50,000
- Lots50,000 ÷ 100,000 = 0.50
Half a standard lot. If price reaches the stop at 1.1030, the loss is 20 pips × $5 per pip = $100, which is the 1% budgeted.
How to use the Forex Position Size calculator
- Select the pair you are trading. The calculator uses it to set the pip size — 0.01 for yen pairs, 0.0001 for the rest.
- Enter your account balance. Use current equity rather than the original deposit if the two differ.
- Set the risk percentage. This is the share of the balance lost if the stop is hit, not the share committed to the position.
- Enter the entry and stop-loss prices you actually intend to use, at full quote precision.
- Set the quote-to-account rate. Leave it at 1 if your account currency matches the second currency in the pair; otherwise enter the rate your broker applies.
- Read the lot size, then round down to the increment your broker accepts. Rounding up risks more than you budgeted.
Limitations of the Forex Position Size calculator
Every calculation makes assumptions. These are the ones that matter here.
- Assumes the stop fills at exactly the stop price. Gaps and slippage, which are common around news releases and at the weekly open, can produce a larger loss.
- Excludes spread and commission. Both add to the cost of a losing trade beyond the calculated risk amount.
- Uses a conversion rate you supply. That rate moves, so the account-currency risk of an open position drifts slightly over time.
- Says nothing about whether the trade is worth taking. It sizes a decision you have already made.
Frequently asked questions about Forex Position Size
What risk percentage should I use?
That is a personal decision that depends on your circumstances, and this forex risk calculator does not recommend a figure. What the arithmetic can tell you is the consequence: at 1% per trade, ten consecutive losses reduce the account by roughly 9.6%; at 5% it is about 40%. The risk of ruin calculator models that relationship directly.
Why does my broker's position size differ slightly?
Most brokers accept lot sizes only in 0.01 increments, so the exact figure has to be rounded. Rounding down risks slightly less than budgeted; rounding up risks slightly more. Brokers may also use a marginally different conversion rate than the one you entered.
Should I use the entry price or the current price?
Use the price at which you intend to enter. For a limit order that is the limit price; for a market order it is roughly the current price, though the fill may differ by the spread.
How does this differ from the lot size calculator?
Both derive a lot size from risk budget and stop distance, but the inputs differ. This one takes entry and stop prices and works out the pip distance for you; the lot size calculator takes the stop distance in pips directly, which is quicker if you already think in pips.
Does the calculator account for leverage?
No, and it does not need to. Position size is set by the stop distance and your risk budget. Leverage determines whether your account has enough margin to open that position, which is what the margin calculator covers.
Last reviewed . See our methodology and editorial policy.
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