How many shares should you actually buy?
Enter your account size, where your stop goes, and how much of the account you are willing to risk. You get a share count. No signup, no card, and nothing you type leaves your browser.
The price at which you accept the idea was wrong and get out.
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The formula, in full
There is no proprietary maths here. Position sizing is one line of arithmetic that every trading desk uses, and it is worth being able to do it in your head:
shares = (account × risk%) ÷ |entry − stop|
The order matters. You decide what you are willing to lose first, then the market tells you how many shares that buys. Most people do it backwards — they pick a share count that feels right, then discover what they stood to lose only after it went against them.
Worked example
A $5,000 account, risking 1% per trade. That is $50 at stake. The setup gives an entry at $18.40 and a sensible stop at $17.60, so the distance is $0.80 per share. $50 ÷ $0.80 = 62.5, rounded down to 62 shares. Those 62 shares cost $1,140.80 — roughly 23% of the account in position value, but still only $50 of actual risk.
That gap between position value and risk is the thing worth internalising. A large position with a tight stop can carry less risk than a small position with a wide one.
Where people get it wrong
| Mistake | What actually happens |
|---|---|
| Treating risk percent as a percent of the stock's price | A 1% move in the stock is not 1% of your account. The two are unrelated. Risk is exposure, measured in your currency, not a percentage change in the underlying. |
| Picking the stop to fit the position size | The stop belongs where the idea is invalidated — below the structure, the level, the wick. Moving it to justify more shares removes the only thing making the number meaningful. |
| Ignoring the position value | The risk can be fine while the position is too large to exit cleanly. On a thin, low-float name your exit moves the price against you. |
| Forgetting fees and slippage | The calculated loss is the best case. A gap through your stop overnight can cost multiples of it. |
What risk percent is reasonable?
There is no universal answer and anyone who gives you one is selling something. What is worth knowing is the arithmetic of drawdown: at 1% per trade, ten consecutive losses costs you roughly 10% of the account and you continue. At 5% per trade, the same ten losses costs about 40% — and recovering from a 40% drawdown requires a 67% gain, not a 40% one.
The calculator will flag anything above 5% for that reason. It still gives you the number, because it is your account.
Common questions
Does this work for options or futures?
Not as written. This calculator assumes one share = one unit of price movement, which is true for equities. Options have contract multipliers and non-linear payoffs; futures have tick values. The logic is the same but the divisor is not.
Should the stop be a hard order or a mental level?
That is a decision about your own discipline and your broker's behaviour outside regular hours, not something a calculator can answer. What the arithmetic assumes is that you actually get out at the stop price, which a gap will not honour.
Is anything stored?
No. There is no server call on this page, no cookie, no local storage, and no analytics event carrying your inputs. Open your browser's network tab and type in the fields — nothing happens. This is deliberate: the moment we started storing your account size, we would be building a different and more heavily regulated product.
The rest of the set
All free, all in-browser, none of them ask for an email to work.