Position Size Calculator
A position size calculator tells you how many shares or units to buy so a single trade never risks more than you intend. Enter your account size, risk percentage, entry, and stop loss to instantly size the trade, set profit targets, and see your risk before you click buy.
Define Your Trade
What are you trading and where are you getting in?
Pro Tips for Risk Management
The 2% Rule
Never risk more than 2% on a single trade to survive losing streaks
2:1 Minimum R:R
Only take trades where potential profit is at least 2x your risk
Plan Before Entry
Define your stop and targets BEFORE entering - never during
How to size a position
Position sizing is the process of deciding how much to buy so that a single trade risks only a small, fixed portion of your account. Follow these steps to size any trade consistently:
- 1
Set your risk per trade
Choose a fixed percentage of your account to risk, commonly 1-2%. On a $10,000 account, 1% means a maximum loss of $100 on the trade.
- 2
Measure your stop distance
Find the difference between your entry price and your stop loss. This is your risk per share and defines where the trade idea is wrong.
- 3
Divide to get your size
Divide your dollar risk by your risk per share to get the number of shares or units. Risking $100 with a $2 stop distance gives a 50-share position.
- 4
Confirm your risk/reward
Check that your target offers at least a 2:1 reward-to-risk ratio before entering. Learn more in our risk management guide and how price targets tie into Fibonacci trading levels.
Position Sizing FAQ
How do I calculate position size?
To calculate position size, first decide how much of your account you're willing to lose on the trade (your dollar risk). Then measure your risk per share by taking the difference between your entry price and your stop loss. Divide your dollar risk by the risk per share to get the number of shares or units to buy. For example, risking $200 with a $2 stop distance means a 100-share position.
What is the 1% rule?
The 1% rule is a risk management guideline where you never risk more than 1% of your total account balance on a single trade. On a $10,000 account, that means a maximum loss of $100 per trade if your stop loss is hit. Keeping risk small protects your capital during losing streaks and helps you stay in the game long enough for your edge to play out. Many traders use 1-2% as their limit.
What is a good risk/reward ratio?
A good risk/reward ratio is generally considered to be at least 2:1, meaning your potential profit is at least twice the amount you're risking. With a 2:1 ratio you can be profitable even if you're right less than half the time. Higher ratios like 3:1 give you more margin for error, while ratios below 1:1 require a very high win rate to stay profitable.
Why does position sizing matter more than entries?
Position sizing matters more than perfect entries because it controls how much you lose when a trade goes against you, and losses are inevitable. Even a great entry can wipe out your account if the position is too large, while disciplined sizing lets you survive a string of losses and keep compounding over time. Consistent risk control, not perfect timing, is what separates traders who last from those who blow up their accounts.