Formulas and 2026 figures checked & updated: July 2026
Your inputs
Results
How to Use the Position Size & Risk Calculator
- Enter total account equity.
- Choose the maximum percentage you are prepared to lose.
- Enter the planned entry and stop prices.
- Reduce the result if capital required exceeds available buying power or portfolio concentration limits.
What This Calculator Does
Position sizing connects trade risk to account size instead of choosing an arbitrary number of shares.
A stop order does not guarantee the execution price, so actual losses can exceed the calculated risk during gaps or fast markets.
Formula
Shares = floor((Account size × Risk %) ÷ |Entry price − Stop price|)The result divides a dollar risk budget by the absolute entry-to-stop distance and rounds down to whole shares. It assumes the stop executes exactly at its price and excludes slippage, gaps, commissions, taxes, correlation, leverage, and foreign-exchange effects. Capital required can exceed cash available; the risk rule does not itself impose a buying-power cap.
Examples
One-percent risk
A $50,000 account risks 1% with a $100 entry and $95 stop.
The $500 risk budget divided by $5 risk per share permits 100 whole shares before slippage.
Related Calculators
Try another tool to complete the picture
Continue Your Financial Planning
Methodology
The result divides a dollar risk budget by the absolute entry-to-stop distance and rounds down to whole shares. It assumes the stop executes exactly at its price and excludes slippage, gaps, commissions, taxes, correlation, leverage, and foreign-exchange effects. Capital required can exceed cash available; the risk rule does not itself impose a buying-power cap.
Frequently Asked Questions
Why round shares down?+
Rounding up would exceed the stated risk budget. The calculator uses whole shares; brokerages supporting fractional shares may allow finer sizing.
Does a stop loss guarantee my loss?+
No. A stop typically becomes a market order when triggered and may execute worse than the stop price, especially after a gap or in an illiquid security.
What risk percentage should I use?+
There is no universal safe percentage. Risk tolerance, strategy, volatility, portfolio correlation, liquidity, and maximum drawdown all matter.
Is the Position Size Calculator exact?+
The arithmetic follows the formula shown on this page, but the result is an estimate because real-world rates, fees, taxes, timing, and provider rules can differ. Use the actual figures from your lender, plan, or agency before making a decision.
Does this calculator store my financial information?+
No. The calculation runs in your browser. Saved results remain in local browser storage and are not submitted as an application or professional financial record.
Can I save my results?+
Yes. Use “Save results” to store a snapshot. Without an account it remains in this browser. If you log in, saved scenarios sync securely to your SmartRates account so they are available on your other devices.
How do I share my calculation?+
Click “Share” in the toolbar to copy a link (or open your device’s share sheet). The link encodes your exact inputs, so whoever opens it sees the calculator pre-filled with the same numbers and the same result.
Can I email my calculator results?+
Yes. Click “Email results” to open your default email application with the current inputs, results, and calculator link already included. Review the message and choose the recipient before sending.
Can I export or print my results as a PDF?+
Yes. Click “Export PDF” to open a clean, printable summary of your inputs and results that you can save as a PDF or print. It includes a timestamp and a link back to the calculator.
How accurate are the calculator results?+
The arithmetic follows the formula and assumptions documented on this page. The result is still an estimate because actual rates, fees, taxes, timing conventions, eligibility rules, and provider calculations can differ. Use figures from your official quote, statement, contract, or tax form before making a financial decision.
Which inputs have the biggest effect on the result?+
Rate, time, starting balance, recurring payments or contributions, and fees usually have the largest effects. Change one input at a time to create a conservative, expected, and optimistic scenario instead of relying on a single forecast.
Are taxes, fees, and inflation included?+
Only when they appear as an input or are explicitly described in the methodology. Do not assume an omitted cost is zero. Review the formula and methodology sections to see exactly what is included before comparing the result with an outside quote.
Can this calculator predict future rates or returns?+
No. A calculator projects the assumptions entered; it cannot predict market returns, inflation, variable interest rates, tax-law changes, or provider decisions. Rerun the calculation with several assumptions to understand the range of possible outcomes.
Why might my lender, bank, broker, or tax software show a different result?+
Professional systems may use daily timing, transaction dates, compounding conventions, rounding rules, account-specific fees, credits, eligibility details, or regulations that a general-purpose calculator cannot know. A small difference can be rounding; a large difference usually means an assumption or included cost is different.
Disclaimer: Calculations are for informational purposes only and do not constitute professional financial advice. Please consult with a certified professional before making financial decisions.