Position Size Calculator
The only math that matters in trading. Calculate exactly how many shares to buy to keep your risk under control.
Stop Blowing Up Your Account. Do The Math.
Here is the brutal truth: 90% of traders fail not because they can't read a chart, but because they don't understand position sizing.
You see a setup. You get excited. You go "all in" because you want to double your account in one trade. Then the market moves 2% against you, and you lose 50% of your capital. Game over.
This calculator fixes that. It tells you exactly how many shares (or contracts) to buy so that if your stop loss hits, you only lose a specific, predefined amount (usually 1% or 2%).
The "1% Rule" of Survival
Professional traders rarely risk more than 1% of their total account on a single trade. Why? Because of Drawdowns.
- If you risk 10% per trade and lose 5 times in a row (which happens!), you have lost 41% of your account. You now need to make ~70% profit just to break even.
- If you risk 1% per trade and lose 5 times in a row, you are down 5%. You can make that back in one or two good trades.
How to Use This Tool
- Account Balance: Enter your total trading capital.
- Risk %: How much of your account are you willing to lose on this ONE trade? (Recommended: 1-2%).
- Entry Price: The price you are buying at.
- Stop Loss: The price where you admit you were wrong and sell.
The tool calculates the Risk Per Share (Entry - Stop Loss) and divides your Total Risk Amount by that number to give you the exact quantity to buy.
Common Questions
What if the quantity is too small?
If the calculator says "Buy 5 shares" and you wanted to buy 100, it means your Stop Loss is too wide for your account size. You either need to tighten your stop (risky) or accept that this trade doesn't fit your risk management rules.
Does this work for Options/Futures?
Yes, but you need to be careful. For options, use the premium price for Entry and SL, not the stock price. For futures, remember to account for leverage and lot sizes.
Why is "Capital Required" higher than my balance?
This happens if your Stop Loss is very tight. The math says you can buy a huge number of shares while keeping risk low, but you might not have enough cash to actually buy them. In this case, you are limited by your buying power (margin), not your risk.