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Forex Position Size Calculator

Divide the cash you are willing to lose by the cash you lose per pip, then divide by the stop distance. On a 10,000 USD account risking 1% with a 25-pip stop on GBP/USD, that is 100 USD ÷ (25 × 0.0001 per unit) = 40,000 units, or 0.40 lots. Change the stop and the size changes with it — that is the whole point.

Result

Recommended position size0.40 lots
Rounded to a tradeable size0.40 lots
units40,000 GBP
Amount at risk$100.00
Value of one pip$4.00
Required margin$1,687.76
Share of your equity tied up16.88%

Rates snapshot: 2026-09-01 — Conversions use an indicative rate snapshot, not your broker’s live quote. Treat the result as a planning figure and confirm it in your platform before you trade.

How the calculation works

Position sizing is one division carried out in the right order:

risk amount = equity × risk %
loss per unit = stop distance in pips × pip value per unit
position size = risk amount / loss per unit

The middle line is where account currency enters. Pip value per unit is fixed in the quote currency — always one pip times one unit — and then converted into your account currency. A PLN-denominated account trading GBP/JPY converts yen to zloty; the calculator does it in one step, but it is worth knowing it happened, because it is why the same trade sizes differently on a euro account than on a dollar one.

Why the stop comes first

If you pick the lot size first and then place the stop wherever it fits, you have chosen the size of your loss by accident. Sizing from the stop inverts that: you decide what the trade is worth risking, the chart decides where the stop belongs, and the size is whatever falls out. It is also the only way a losing streak stays survivable — every loss is the same fraction of the account, regardless of which instrument produced it.

Margin is a constraint, not an input

The calculator reports the margin the recommended size ties up. Treat it as a feasibility check. If sizing correctly would consume most of your free margin, the problem is not the sizing method — it is that the account is too small for that instrument at that stop distance.

A worked example

Account capital
$10,000
Risk per trade (%)
1.0%
Stop loss (pips)
25
Currency pair
GBP/USD

$100.00 / (25 × 0.000100)

Recommended position size
0.40 lots
Rounded to a tradeable size
0.40 lots
Amount at risk
$100.00
Value of one pip
$4.00
Required margin
$1,687.76

Worked examples on the English edition use a 10,000 USD account, which is roughly the median funded retail account size quoted in broker disclosures.

Local context

The 1%-per-trade convention comes from US futures literature and assumes an account you are prepared to rebuild. It is a starting point, not a rule. What does not change between markets is the arithmetic: the stop distance and the risk budget decide the size, and the size then tells you how much margin you need — never the other way round.

RegulatorVaries by residence: FCA (UK), ASIC (Australia), CySEC (Cyprus/EU), CFTC & NFA (US)
Maximum leverage30:1 for major pairs under FCA, ASIC and CySEC rules; 50:1 for majors in the US under CFTC/NFA
Account currencyUSD

TODO: zweryfikuj — the English edition serves several tax jurisdictions, so no single rate applies. Do not state one; link readers to their own tax authority.

Common questions

Should the risk percentage be of balance or of equity?
Of equity, meaning balance plus open profit and loss. Using balance while positions are open understates your exposure exactly when it matters most.
Why is the recommended size shown twice?
The exact figure is what the maths gives you; the second line rounds it down to a 0.01-lot step, which is what platforms accept. Rounding down keeps you inside the risk budget — rounding up quietly breaks it.
Does a wider stop mean more risk?
No, if you resize. A 60-pip stop with half the position size risks exactly the same money as a 30-pip stop at full size. The stop distance should come from the chart; the size then follows from it.
The size I get needs more margin than I have. Now what?
That is the calculator telling you something useful: at this leverage, this stop and this risk budget are not compatible with this account. Widen the stop and cut the size, or trade a smaller instrument — do not raise the risk percentage to make the numbers fit.

Method and sources

Last updated: · Rates snapshot: 2026-09-01

Conversions use an indicative rate snapshot, not your broker’s live quote. Treat the result as a planning figure and confirm it in your platform before you trade.

  • Pip values in this tool come from the shared engine — see engine/pipValue.ts
  • Rate snapshot — see engine/rates.ts

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