Position Size Calculator
A position size calculator tells you how many shares, units, or lots to buy so t
A position size calculator tells you how many shares, units, or lots to buy so t
How to use Position Size Calculator
- Enter your account balance and set how much to risk on the trade, either as a percentage of your account or a fixed amount.
- Type in your planned entry price and your stop-loss price.
- Read your position size and round it down to a whole number of shares or lots before placing the trade.
About Position Size Calculator
A position size calculator tells you how many shares, units, or lots to buy so that if your stop-loss is hit, you lose no more than a set amount of your account. It uses the standard risk-based formula: amount at risk divided by the price distance from your entry to your stop-loss equals your position size. Set your risk either as a percentage of your account (many traders use 1-2%) or as a fixed cash amount.
Enter your account balance, your chosen risk, an entry price, and a stop-loss price. The tool works out the exact position size along with the total amount at risk, the position value, the risk per unit, the distance to your stop as a percentage, and how large the position is relative to your account. It works for long or short setups automatically based on whether your stop sits below or above your entry.
Everything is calculated locally in your browser using the numbers you type. Nothing is uploaded, saved, or sent anywhere, and no account is needed. It does not include broker commissions, spreads, slippage, overnight financing, or currency conversion between the traded instrument and your account, so treat the result as a clean starting point and round down to a whole, tradeable size. This is an arithmetic tool, not financial advice.
Frequently asked questions
- How is position size calculated?
- Position size = amount you are risking / price distance between your entry and stop-loss. For example, risking $100 with an entry at $100 and a stop at $95 (a $5 distance) gives 20 units. That way, if the stop is hit you lose exactly your intended $100.
- What risk percentage should I use per trade?
- That is your decision and depends on your strategy and risk tolerance. Many traders limit risk to 1-2% of account equity per trade so a losing streak does not do serious damage. This tool lets you enter any percentage or a fixed cash amount instead.
- Does it work for forex and crypto as well as stocks?
- Yes. The math is the same for any instrument priced in your account currency: it returns units, which you interpret as shares, coins, or lot units. Note it does not convert pip or contract values across a different quote currency, so for forex confirm the per-unit value matches your account currency.
- Are commissions, spread, and slippage included?
- No. The result is based purely on entry, stop, and risk. Real fills can differ due to spread and slippage, and commissions add to your loss, so size a little more conservatively than the raw number if those costs are significant for you.
- Is my data private?
- Yes. Every calculation runs in your browser with JavaScript. Your account balance, prices, and risk settings are never sent to a server, stored, or shared. Closing the tab clears everything.
- Why should I round down instead of up?
- Rounding up would push your loss above the risk you set. Always round the position size down to the nearest whole share or lot your broker allows so your worst-case loss stays inside your limit.