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Position size calculator for prop firm traders.
Enter your account, your risk and your stop loss. You get the lots to open, the money at risk, and how many losing trades in a row you can take before your prop firm's daily loss limit.
Lots to open
0.50lots
$500 at risk if the stop loss is hit
$5,000 of room left today
The calculator runs in your browser: nothing you type is sent or saved. It does not include commissions, swaps or spread; leave a little room for them.
How the lot size is calculated.
Two numbers decide the size: the money you accept to lose on the trade, and how much one lot loses when the price reaches your stop loss.
Example on gold. A 100,000 dollar FTMO account, 0.5% risk per trade, stop loss 10 dollars away. The risk is 500 dollars; one lot loses 10 × 100 = 1,000 dollars at the stop, so the size is 500 ÷ 1,000 = 0.50 lots.
What it means for the daily limit. FTMO's 2-Step allows a 5% daily loss, 5,000 dollars on this account: at 500 dollars a loss, that is 10 losing trades in a row. At 1% risk it is 5; on the 1-Step, where the daily limit is 3%, it is 3.
| Risk per trade | Losses to the daily limit, 5% | Losses to the daily limit, 3% |
|---|---|---|
| 0.25% | 20 | 12 |
| 0.5% | 10 | 6 |
| 1% | 5 | 3 |
| 2% | 2 | 1 |
Losing streaks of 5 or more trades are normal even for a strategy that makes money, which is why most prop traders risk between 0.25% and 1% per trade.
Questions about position size.
How much should I risk per trade on a prop firm challenge?
Most prop traders risk between 0.25% and 1% of the account per trade. The daily loss limit decides it: with a 5% daily limit, 1% risk lets you lose 5 trades in a row before the day ends the challenge; with a 3% daily limit it is only 3.
Why is the lot size on gold so different from forex?
Because one lot is a different amount of each asset. On most brokers one lot of gold is 100 ounces, so a 1 dollar move is worth 100 dollars, while one lot of EURUSD is 100,000 euros, so a 1 pip move is worth about 10 dollars.
What is the value of one lot on US100 or US30?
It depends on the broker. Many prop firm servers use a contract where one lot moves 1 dollar per index point, others 10 or 20. Open the symbol's contract specification in MetaTrader 5 and enter that value in the calculator.
Does the daily loss limit include open trades?
On most prop firms, yes: the limit is measured on equity, so a floating loss counts as soon as it happens. That is why the calculator counts the room left today, including today's result.
What is a trailing maximum loss?
A maximum loss that moves up as the account makes new highs, instead of staying fixed at the starting balance. On FTMO's 1-Step the 10% maximum loss trails the highest balance, so profits raise the floor.
Is my data saved?
No. The calculation runs entirely in your browser: nothing you enter is sent to TierAlba or stored.
Prop firm limits checked on 1 November 2026. Rules change: read your firm's current rules before you trade.
Never break the daily limit by surprise.
Tier Guard watches your prop account live and shows the room left before every limit. Free on one account, on MetaTrader 5 and cTrader.
Trading involves a high level of risk and may not be suitable for everyone. TierAlba provides software and services and does not give financial advice.