Tools / Position Size
How big should this trade be?
Size a trade so hitting your stop costs exactly the share of the account you chose to risk.
FormulaUnits = (Account × Risk %) ÷ (Stop Pips × Pip Value)
The formula above is exactly what this calculator runs, in full view. Never trust a number blindly, verify it: check it against your own broker's or prop firm's figures before you rely on it. You are responsible for every value you enter here; the result is for reference and educational purposes only, never financial advice, and Traderista accepts no responsibility for the financial decisions you make from it.
These thresholds are based on widely-accepted prop-trading community norms. They are not investment advice.
Same calculator, three outcomes
Reading the calculator in four steps
Pick your instrument. Sets the pip size and contract size the rest of the math uses.
Enter your account balance. The base the risk percentage is measured against.
Set the percent you're willing to risk. The result panel tints amber at 2% and red past 4%, industry-common caps, not a rule about your account.
Set your stop-loss distance in pips. Where the trade idea is wrong. The panel then shows the position size that risks exactly the dollar amount above.
Risk % vs. what the calculator shows
| Risk % | State | What it means |
|---|---|---|
| ≤ 2.0% | Safe | Within the common per-trade risk range |
| 2.0–4.0% | Caution | Above the common range, not yet extreme |
| > 4.0% | High risk | One stop-out costs a large share of the account |
What keeps position size honest, and what breaks it
- Setting the stop-loss distance from market structure, then sizing the position to fit the risk you chose.
- Keeping risk % consistent trade to trade instead of sizing up after a loss to "win it back."
- Re-running the calculator when the account balance changes, not reusing yesterday's lot size.
- Widening the stop after opening the trade, which quietly raises the real dollar risk above what was sized.
- Sizing from a round lot number instead of the risk percentage.
- Ignoring the guardrail because "this trade feels different."
Frequently asked questions
How do you calculate position size for trading?
Multiply account balance by the risk percentage to get the dollar amount at risk. Divide that by the stop-loss distance (in pips) times the pip value to get the position size.
What is a good risk percentage per trade?
This calculator turns amber above 2% and red past 4%, a common prop-trading convention. Many traders settle on 1–2% as a starting point, not a rule this calculator enforces.
Why does the calculator ask for an instrument?
Pip size and contract size differ by instrument, gold's lot is 100 ounces, not the 100,000-unit lot most currency pairs use. Picking the instrument gets both right automatically.
Does this calculator store my account balance?
No. Everything runs in your browser. Traderista never fetches, stores, or transmits the numbers you type in.
Use this alongside
Traderista provides educational information and historical data only. Nothing here is financial advice. Trading involves substantial risk of loss. Past performance does not indicate future results.