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MasterMath

Forex Lot Size Calculator

With a 10,000 account risking 1% and a 20-pip stop, you can trade 0.5 lots. Each pip is then worth 5, so the stop costs exactly the 100 you were willing to lose.

Currency and number format for

Lots you can open

—

Lots you can open—
You risk—
In mini lots—
In micro lots—
Units of the base currency—
Each pip moves you—

How this was worked out

    Indicative result. Nothing here is investment advice. Pip values vary by pair and by account currency; check yours with your broker.

    The formula

    lots = (capital × risk %) ÷ (stop in pips × pip value per lot)

    Where it comes from

    In forex, position size is measured in lots and risk is measured in pips. A standard lot is 100,000 units of the base currency and moves about 10 per pip on most pairs, so the lot size is whatever makes your stop distance cost exactly what you are prepared to lose.

    How to work it out by hand

    1. Work out the cash you are risking: capital times the risk percentage
    2. Multiply the stop distance in pips by the pip value of one standard lot
    3. Divide the first by the second
    4. The result is the lot size, in mini or micro lots if it is below one

    What is worth knowing

    Two things trip people up. Pip value is only about 10 per standard lot when the quote currency matches your account currency — on cross pairs and on anything quoted in a third currency it moves with the exchange rate, so check it rather than assuming. And a tighter stop does not reduce risk, it increases position size for the same risk: halving the stop distance doubles the lots, which doubles what a gap through the stop costs you. The cash at risk is the constant here; everything else is derived from it.

    Frequently asked questions

    What is a standard lot?

    100,000 units of the base currency. A mini lot is 10,000 and a micro lot is 1,000, which is why the answer is often expressed in fractions.

    Is a pip always worth 10?

    Only when the quote currency matches your account currency, roughly. On other pairs it moves with the exchange rate, so confirm it with your broker.

    Does a tighter stop mean less risk?

    No. It means a bigger position for the same risk. That is fine until the stop gaps, at which point the larger position costs you more.

    What risk percentage should I use?

    One percent per trade is the usual convention. Leverage in forex makes it very easy to size positions that a normal losing streak would wipe out.