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Position Size Calculator: Formula, Examples for Forex, Crypto and Stocks

The position size formula with worked examples for forex lots, crypto coins and stock shares.

The formula

Position size = (account × risk %) ÷ (stop distance × value per unit of price). Decide the account risk first, then the stop from the chart, then solve for size.

Forex example

Account $10,000, risk 1% = $100. EUR/USD stop 20 pips. A pip on one standard lot is about $10, so 20 pips is $200 per lot. Size = $100 ÷ $200 = 0.5 lots.

Crypto and stocks

For BTC with a $100 risk and a stop $1,500 below entry, size = 100 ÷ 1,500 = 0.067 BTC. For a stock with a $2 stop and $100 risk, size = 50 shares. Remember to check that the total position value fits your buying power.

Common mistakes

Using the wrong pip value for JPY or non-USD pairs, ignoring spread and slippage in the stop distance and changing the stop after entry without recalculating. Use a calculator every time until it is automatic.

Example: a stock trade

Account $20,000, risk 0.5% = $100. You buy a stock at $50 with a stop at $48.50, so the risk is $1.50 per share. Size = $100 ÷ $1.50 = 66 shares, a position worth $3,300 (16.5% of the account).

If the stock gaps below your stop at the open, the loss can be larger than planned, so keep the total risk low on gap-prone names.

What the calculator cannot know

A calculator does not know about gaps, slippage, widening spreads, or correlated trades that you hold at the same time. Leave a margin of safety: if the calculator says 0.5 lots, consider 0.4. Check that your combined open risk across all trades stays under your chosen limit, such as 3% of the account.

Key takeaways

• Risk % and stop distance set the size.
• Know the pip value of your pair.
• Crypto and stocks use price units.
• Recalculate if the stop changes.

Related

• Position size calculator

Educational content, not financial advice.