Position Size Calculator

Worked Examples

How to Use This Calculator

1. Choose your trade direction — select Long if you're buying, Short if you're selling.
2. Enter your account size — the total capital in your trading account.
3. Set your risk percentage — most traders risk 1-2% per trade. This is the maximum you're willing to lose.
4. Enter your entry price — the price at which you plan to open the position.
5. Set your stop loss price — below entry for longs, above entry for shorts. This is where you'll exit if the trade goes against you.
6. Click Calculate — the calculator returns the number of shares to buy or sell, your dollar risk, and position value.

Frequently Asked Questions

What is a good risk percentage per trade?

Most professional traders risk between 0.5% and 2% of their account per trade. Beginners should start at 1% or lower. The key is consistency — even a small edge compounds over time when risk is controlled.

How does stop loss distance affect position size?

A wider stop loss means fewer shares (smaller position), and a tighter stop means more shares (larger position). The calculator adjusts automatically so your total dollar risk stays the same regardless of stop distance.

Why are shares floored to whole numbers?

Most brokers require whole-share orders for stocks. Flooring ensures you never exceed your intended risk. Some brokers allow fractional shares — in that case, your actual position could be slightly larger.

Does this work for options or futures?

This calculator is designed for stocks and ETFs. For options, the risk-per-contract calculation is different because of leverage and premium. For futures, use contract-based position sizing with tick values.

What if my position size is 0 shares?

This means your stop loss is too far from entry relative to your account risk. Either tighten your stop, increase your risk percentage, or increase your account size. A 0-share result means the trade doesn't fit your risk parameters.