Position size
Risked amount
100.00 $
Size (lots)
0.50 lots · 50,000 Units
Pip value / lot
10.00 $
Stop loss
1.0830 (−20 pips)
Take profit
1.0890 (+40 pips)
Risk/reward ratio
1:2.00
Indicative pip values based on standard contract specs - always verify the size with your broker before executing.
This position size calculator works out how many lots to open so that a single trade risks exactly a chosen percentage of your account if the stop loss is hit. Enter your balance, the percentage you are willing to lose and your stop distance in pips · it returns the amount at risk, the position size in lots and units, the pip value, and the exact stop and target prices.
The lot figure answers one simple question: at this size, a close at the stop costs the stated amount, no more and no less. The calculation takes into account the chosen instrument (currency pair, gold, index, crypto...), its contract size and quote currency, then converts everything into your account currency. It runs on the same calculation engine as the StrixFX app.
The formula explained
Amount at risk = account balance × risk percentage ÷ 100. Then: lots = amount at risk ÷ (stop distance in pips × pip value for 1 lot). The pip value depends on the instrument: pip size × contract size (100,000 units for a standard forex lot), converted into your account currency. The result is then truncated down to the nearest 0.01 lot, never rounded to the closest: rounding up would risk more than the requested percentage. Example: $10,000, 1% risk and a 20 pip stop on EURUSD give $100 at risk ÷ (20 × $10) = 0.50 lots.
A worked example
First step, the amount at stake: $10,000 × 1% = $100. Second step, the cost of one lot: on EURUSD a pip is worth $10 per standard lot, so a 35 pip stop costs 35 × 10 = $350 per lot. Third step, the division: 100 ÷ 350 = 0.2857 lots. The calculator shows 0.28, not 0.29: at 0.29 lots, a close at the stop would cost $101.50, more than what you decided · at 0.28 it costs $98. Between exceeding your risk and staying under it, it always stays under. Full result: 0.28 lots, i.e. 28,000 units, for an actual risk of $98.
Reference table · $10,000, 1% risk, EURUSD
The same amount at stake, six stop distances · every line comes from the calculator's exact engine, truncation included.
| Stop distance | Calculated size | Loss if the stop is hit |
|---|---|---|
| 10 pips | 1.00 lot | $100.00 |
| 20 pips | 0.50 lots | $100.00 |
| 35 pips | 0.28 lots | $98.00 |
| 50 pips | 0.20 lots | $100.00 |
| 75 pips | 0.13 lots | $97.50 |
| 100 pips | 0.10 lots | $100.00 |
What the number does not tell you
This calculation is exact, and on its own it protects you from nothing. It assumes your stop is filled at the intended price: around news or a weekend open, price can jump past it, and the actual loss then exceeds the calculated amount. It does not judge the trade: a perfect size on a bad idea is still a bad idea, just correctly sized. It holds for one isolated trade: three positions on pairs that move together are not three independent risks · for the combined exposure, the portfolio risk calculator is the one that answers. Finally, the pip value comes from a reference table: on pairs not quoted in dollars, your broker may show a slightly different figure.
The classic mistake
It is almost universal: decide on a “reasonable” size first, then place the stop where it remains affordable. In that order, when the stop costs too much, you pull it closer so the trade fits · and a stop placed for budget reasons, not structure, is a stop that will get hit. The calculation only works the other way around: the stop goes where your analysis says you are wrong, however far that is, and the size adapts, never the reverse. If the size that comes out looks tiny, the calculation is not wrong: that trade, at that risk, is simply worth no more than that.
Frequently asked questions
What is a pip, and how is its value worked out?
A pip is the conventional smallest price step of an instrument: 0.0001 on most currency pairs, 0.01 on yen pairs. Its value for 1 lot is that step multiplied by the contract size, converted into your account currency. On EURUSD, one pip is worth $10 per standard lot. The values shown are indicative: every broker has its own contract specifications, which can differ slightly.
Why is the number of lots rounded down?
Because rounding to the nearest value could push the risk above what you asked for: 0.3077 lots rounded to 0.31 risks more than the entered amount. The calculator therefore always truncates down to the nearest 0.01 lot, the size step accepted by most platforms. Your actual risk is at most equal to the one you requested, never above it.
Does it also work for gold, indices or Bitcoin?
Yes. The calculator ships with an instrument catalogue and the matching contract sizes: major and exotic currency pairs, metals such as XAUUSD (100 ounces per lot), indices, commodities, stocks and cryptocurrencies. Just type the symbol into the instrument field. If a symbol is unknown, the calculation falls back to EURUSD conventions, so check that the displayed pip value matches your instrument.
Why does the size change when I change the account currency?
Because the amount at risk is expressed in your account currency, while the pip value is first computed in dollars, then converted with a reference rate. With identical figures, €10,000 and 1% put €100 at stake, which weighs more than $100 once converted: with the same 35 pip stop, the calculation gives 0.30 lots instead of 0.28. That is not an error, that is the conversion.
What if the result is smaller than my broker's minimum size?
Most platforms accept nothing below 0.01 lots. A $500 account at 1% risk with a 100 pip stop gives $5 ÷ $1,000 = 0.005 lots · the calculator shows 0.00. That zero is information, not a defect: at that capital, that stop and that risk, no allowed size respects the amount you set. Taking 0.01 lots anyway would risk $10, that is 2% of the account instead of 1% · double what was decided. The numbers are in front of you · the conclusion is yours.
See also
Profit
Work out the profit or loss of a forex, index or metals trade from the entry price, the exit price and the lot size. Free in-browser calculator, no sign-up.
Pip value
Work out what one pip is worth for any currency pair, based on your lot size and account currency. Free, instant, and everything runs in your browser.
Margin
Work out the margin a forex or CFD position ties up at any leverage: notional value and required margin, in 9 account currencies, free and with no sign-up.