Question 1

What is position sizing in stock trading?

Accepted Answer

Position sizing is the process of deciding how many shares to buy in a single trade so that the maximum loss does not exceed a fixed percentage of your total portfolio. The standard rule is to risk no more than 1–2% of capital on any one trade. The formula is: Max shares = (Portfolio Value × Risk %) / (Entry Price − Stop Loss).

Question 2

What is a good risk per trade percentage?

Accepted Answer

Most professional traders use 1% per trade as the standard. Beginners should start with 0.5–1% to limit drawdowns while learning. Risking more than 2% per trade is considered aggressive — a streak of 5–6 losses can erode 10–15% of capital before a single profitable trade. Conservative long-term investors often use 0.25–0.5% per individual stock pick within a diversified portfolio.

Question 3

How does the stop loss affect position size?

Accepted Answer

A wider stop loss (further from entry price) reduces the number of shares you can buy at the same risk %, because each share now carries more risk. A tighter stop loss allows you to hold more shares for the same dollar risk, but it also increases the chance of being stopped out by normal volatility. The right stop loss depends on the stock’s volatility, support/resistance levels, and your time horizon — not on how many shares you want to own.

Question 4

Does this calculator work for forex position sizing?

Accepted Answer

Yes. The same formula applies to forex: replace Entry/Stop Loss prices with the entry rate and stop rate, and "shares" becomes the position size in lots or units. For pip-based stops, divide your max risk in dollars by (pip distance × pip value per lot) to get position size in lots. The risk per trade rule (1–2%) is the same across asset classes.

Question 5

Should I include broker fees and slippage in this calculation?

Accepted Answer

Yes — for small positions, fees and slippage can significantly increase real risk. Subtract estimated round-trip costs from your max risk dollars before dividing by risk per share. Example: if you risk $100 per trade and pay $4 in commissions plus $2 in expected slippage, calculate position size with $94 instead of $100. For commission-free brokers and large-cap liquid stocks this adjustment is rarely material.

Stock Position Size Calculator — Risk-Based Position Sizing & Risk/Reward