How big a position may be
Position size is the one decision that is arithmetic rather than judgment. Your balance, the share of it you are willing to lose on one trade and the distance to your stop give exactly one answer, in the currency your account is in.
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Your trade
Position size
Lot size
0.50
50,000 units
- Money at risk
- US$100.00
- One pip, 1 lot
- US$10.00
A pip is 0.0001, or 0.01 on a pair that holds the yen. Rates are the ECB reference set of 2026-09-23, so the result is close to your broker's and not identical: a broker converts at its own rate and adds its spread.
Three things the sum will not do for you
It does not set the stop. That distance comes from the chart, from the point where your idea is wrong. A stop chosen to fit a lot size is not a stop.
It does not know your other positions. Two trades that share a currency are one bet in two positions, and on a macro day they move together.
It does not know your firm. A daily loss limit caps the day, not the trade, and that is the number that ends challenges. The rules per firm.
Questions about position size
How do you calculate position size in forex?
Divide the money you are willing to lose by the distance to your stop in pips, and then by what one pip is worth on that pair at one lot. The calculator on this page does the conversion into your account currency for you.
How much should I risk per trade?
That is your decision and your firm's. What the arithmetic can tell you is the consequence: at 1 percent a run of five losses costs about 5 percent, which is inside most daily and maximum loss limits, and at 3 percent it is not.
Why is the lot size different on each pair?
Because a pip is paid in the second currency of the pair and then converted into yours. The same twenty pip stop is a different amount of money on every pair. What a pip is worth
Do you store what I type here?
No. The sum runs in your browser, nothing is sent anywhere and there is nothing to sign up for.