Position size calculator
Decide what you are willing to lose, then let the stop distance tell you the size. This is the calculation that separates traders who survive a losing streak from traders who do not — and it takes one number from you that most position size tools quietly ignore: the smallest lot your broker will actually accept.
Position size for 1% risk
0.50 lots
Exact size is 0.5000 lots; rounded down to the 0.01 lot step your broker accepts.
Risk budget
$100
1% of $10,000
Actual loss at stop
$100.00
after rounding to a tradable size
Value per pip
$5.00
$10.00 per standard lot
The arithmetic
lots = (account x risk%) / (stop in pips x value per pip)
= ($10,000 x 1%) / (20 x $10.00)
= 0.5000 lotsWhy sizing beats every other risk control
A stop loss caps the price at which you exit. Position size caps the money that exit costs you. Traders obsess over the first and improvise the second, which is why two people can trade the same signals with the same stops and end the year in completely different places.
Fixing risk as a percentage of the account also makes losing streaks survivable by construction. At 1% per trade, ten consecutive losses cost roughly 9.6% of the account — unpleasant, entirely recoverable. At 5% per trade the same streak costs 40%, and recovering from that requires a 67% gain. The sizing rule is what decides which of those two runs you are having.
Pip value is not always $10
Most sizing errors trace back to assuming every pip is worth $10 per lot. That is true only for pairs quoted in USD. A USD/JPY pip is worth about $6.47, so the same formula with $10 undersizes the position by a third. Gold is further off again: a 100oz contract moves $1 per one-cent tick, and stops are usually set hundreds of ticks wide. This calculator derives pip value from contract size, pip size and quote currency for every instrument, so the arithmetic stays correct when you switch markets.
See the full table on the pip value calculator.
Questions
- How do you calculate forex position size?
- Position size in lots = (account balance x risk percentage) / (stop loss in pips x pip value per lot). On a $10,000 account risking 1% with a 20 pip stop on EUR/USD, that is $100 / (20 x $10) = 0.5 lots. The only part that varies between instruments is pip value: $10 per standard lot on USD-quoted pairs, about $6.47 on USD/JPY, and $1 per one-cent tick on a 100oz gold contract.
- Should I round position size up or down?
- Down, always. Rounding up means risking more than you decided to risk, which defeats the purpose of sizing the trade in the first place. This calculator floors to your broker lot step and then shows the loss you would actually take at that size, so you can see the difference rounding made.
- What if the calculated size is below my broker minimum?
- Then the trade does not fit your account at that stop distance. Your three options are a wider account, a tighter stop, or skipping the trade — but not taking the minimum lot and hoping. The calculator flags this case and shows what the minimum position would actually risk, which is usually a percentage nobody would accept if they saw it written down.
- Does leverage affect position size?
- No, and this is the most expensive misunderstanding in retail trading. Leverage determines the margin you must post to open a position; it has no bearing on how much you lose if the stop is hit. Position size and stop distance determine risk. Leverage only determines whether your broker lets you open the position at all.