Position Size Calculator
This free position size calculator determines exactly how large a trade you should take based on your account size, the percentage you are willing to risk, and your stop-loss distance. Proper position sizing is the foundation of risk management — it ensures a single losing trade never damages your account. Enter your numbers and the calculator returns the correct lot size (forex) or number of shares (stocks).
How to Use the Position Size Calculator
- Enter your account balance.
- Enter the percentage of your account to risk (commonly 1%–2%).
- Enter your stop-loss distance (in pips or price).
- Calculate — see your position size.
The Position Size Formula
Position Size = (Account × Risk %) ÷ (Stop-Loss × Value per Unit)
First find the dollar amount you are risking (account × risk %), then divide by the loss per unit at your stop. For example, a $10,000 account risking 1% ($100) with a 50-pip stop where each pip is worth $1 per mini-lot gives a position of 2 mini-lots.
Why Position Sizing Matters
| Risk per Trade | Losing Streak to Halve Account |
|---|---|
| 1% | ~69 trades |
| 2% | ~34 trades |
| 5% | ~14 trades |
| 10% | ~7 trades |
Risking a small, fixed percentage per trade lets you survive losing streaks that would wipe out an over-leveraged account.
Risk Management Tips
- Risk a consistent small percentage (1%–2%) on every trade.
- Always set a stop-loss before entering.
- Size the position to the stop, not the other way around.
- Account for the value per pip or per point of the instrument.
Note: Trading involves risk. This tool is for educational position sizing, not financial advice.
Frequently Asked Questions
How do you calculate position size?
Divide the dollar amount you are risking (account × risk %) by the loss per unit at your stop-loss. The result is the number of lots or shares to trade.
What is a lot size in forex?
A standard lot is 100,000 units, a mini-lot 10,000, and a micro-lot 1,000. The calculator converts your risk into the appropriate lot size.
How much should I risk per trade?
Most risk-management approaches suggest 1%–2% of your account per trade, which lets you withstand losing streaks without major damage.
Why size the position to the stop-loss?
Because your stop defines your maximum loss per unit, sizing to it ensures your total risk stays at your chosen percentage regardless of where the stop is.
Is this position size calculator free?
Yes — it is completely free, requires no signup, and works for forex and stocks.