Position size (lot) calculator

Work out how many lots to trade from your balance, your risk percent or amount and your stop-loss distance in pips.

This calculator tells you how many "lots" (the trade size) to open so you only risk what you decide if the stop loss is hit. Fill in your balance, how much you want to risk and how far your stop is, and it gives you the exact size.

Trade details

Account balance

Account currency

Instrument

Risk per trade

Stop-loss distance (pip (0.0001))

Pip value per standard lot calculated automatically: 10.00 USD

Result

Recommended lot size

0.05 lots

5,000 units

Target risk: 10.00 USD
Actual risk with the rounded lot: 10.00 USD

Calculation details

Exact lot (unrounded): 0.0500
Pip value used: 10.00 USD

Educational tool, not financial advice

Contract sizes and pip values are indicative and can vary between brokers, especially for gold and silver. Always check the exact symbol specification in your platform before trading.

Risk simulation (risk of ruin)

With the per-trade risk you set above, this simulation runs 1,500 possible "lives" of your account and tells you what percentage would end up blowing it up, and how much you could gain or lose. It doesn't predict the future: it just does the math on your own risk management.

Win rate %

Reward/risk ratio (R)

Number of trades

Ruin = loss of…

Risk of ruin (−50%)

0.0%

of the 1,500 simulations hit that level

Prob. of ending in profit

96.9%

after 100 trades

Median final balance

1,274

USD · from 1,000

50% central (p25–p75) 90% central (p5–p95) mediana nivel de ruina (−50%)

Bad scenario (p5): 1,043 USD
Good scenario (p95): 1,594 USD
Typical drawdown (median): 6.9%
Drawdown in the worst 5%: 12.9%

How is this calculated?

Fixed-fraction Monte Carlo method: each account "life" plays the given number of trades, winning or losing at random according to your win rate, risking the % of balance you set above on each. 1,500 lives are run and it counts how many dropped to the ruin level. The same parameters always produce the same result (fixed seed).

Educational tool, not financial advice

The simulation assumes each trade is independent and that your win rate and ratio stay constant — in reality they vary. Use it to compare risk levels, not as a prediction.

How position size is calculated

Position size comes from three figures you decide: how much capital you hold, what share of it you accept risking on the trade, and how far away you place the stop loss. The maths spreads that risk across the pips of that distance, and turns the result into lots using what a pip is worth on your pair.

Lots = (Balance × Risk %) ÷ (Stop distance in pips × Pip value per lot)

A worked example

On a €5,000 balance, if you decide to risk 1% that is €50 on the trade. With the stop 25 pips away and a pip worth €10 per standard lot, the risk per lot would be €250. Dividing 50 by 250 gives 0.20 lots. Move the stop to 50 pips and the same euro risk calls for half the size: 0.10 lots.

Frequently asked questions

Why does the lot size change when I move my stop?: Because the money at risk stays fixed while the distance changes. A wider stop spreads the same euros across more pips, so size drops. That relationship is why stop and size cannot be decided separately.
Does this work for indices, commodities or crypto?: The formula is the same; what changes is the pip or point value, which depends on each instrument's contract. If you trade something other than a currency pair, check with your broker what a point is worth for the contract size you use.
What if my account currency differs from the pair?: Then the pip value has to be converted into your account currency. The calculator does it with the European Central Bank's daily reference rates and shows the date of the figure; you can also enter the value by hand if you prefer your broker's.

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