Free calculator
Position Size Calculator
Enter your account size, the percentage you're willing to risk, and your entry and stop prices. You get back the exact number of shares that keeps a stop-out inside your risk budget.
Position size
Enter your numbers to calculate.
- Risk budget
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- Risk per share
- Actual risk
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- Position value
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- % of account
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- Potential reward
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- Reward : risk
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Calculations run entirely in your browser. Nothing you type is sent anywhere, stored, or logged.
Why position sizing matters more than entries
Most traders spend their attention on deciding what to buy. Position sizing decides how much, and it is the variable that determines whether a losing streak is an inconvenience or the end of your account.
Consider two traders with $25,000 who take the same ten trades and lose all ten. The one risking 1% per trade finishes with about $22,600 and can keep working. The one risking 10% finishes with about $8,700 and now needs a 187% gain just to get back to even. Same analysis, same entries and same exits, with size the only difference.
How the calculation works
The whole method is three steps, and it starts at the loss you will accept.
- Risk budget: the most you will lose on this trade.
Account balance × Risk % = Risk budget
$25,000 × 1% = $250 - Risk per share: what one share costs you if the stop is hit.
|Entry − Stop| + fees = Risk per share
|$72.60 − $64.00| = $8.60 - Position size: divide one by the other and round down.
Risk budget ÷ Risk per share = Shares
$250 ÷ $8.60 = 29 shares
Twenty-nine shares at $72.60 is a $2,105 position, about 8% of the account. If the stop is hit, the loss is $249. That is the number you decided on before you entered, and it did not depend on how confident you felt.
Choosing your risk percentage
| Risk per trade | Suits | Account after 10 straight losses |
|---|---|---|
| 0.5% | Large accounts, new traders, high trade frequency | 95.1% |
| 1% | The standard default for most traders | 90.4% |
| 2% | Experienced traders with a tested edge | 81.7% |
| 5% | Rarely justified | 59.9% |
| 10% | Not a risk strategy | 34.9% |
Ten losses in a row sounds extreme. It is not. A strategy that wins 50% of the time will produce a ten-loss streak roughly once every thousand trades, which for an active trader is a matter of a few years. Size for the streak you will eventually hit, however unlikely it feels today.
What you still have to judge yourself
- Gaps and slippage. A stop is an order, not a guarantee. Overnight gaps can fill you well below your stop price, especially around earnings.
- Correlation. Five separate 1% positions in the same sector are closer to one 5% position than to five independent bets.
- Total open risk. Cap the sum of all open positions' risk (commonly at 5 to 6% of the account) as well as each individual trade.
Once the size is settled, check the trade is worth taking at all with the risk/reward calculator, and read how professional risk management fits together.
Frequently asked questions
What is position sizing?
Position sizing is deciding how many shares or contracts to buy so that, if your stop loss gets hit, you lose only the amount you already decided you could. It starts from the loss you'll accept and works back to a share count.
How much of my account should I risk per trade?
Most professional risk frameworks put it between 0.5% and 2% of account equity per trade, and 1% is the common default. The exact number matters less than applying it consistently. A trader risking 1% can lose ten trades in a row and still hold 90% of their capital. A trader risking 10% would be down roughly 65%.
Why is my calculated position larger than my account?
Because a tight stop means a small risk per share, so it takes a lot of shares to use up your risk budget. The calculator flags it when that happens. Unless you're using margin, cap the position at what your cash can buy. That does mean you're risking less than your target, and that's fine.
Should I include commissions and fees?
For most stock trading at modern commission rates the effect is small, though it isn't zero. Add the round-trip cost to your risk per share if you're trading a small account, small position sizes, or markets with meaningful spreads. It matters most to high-frequency and small-size traders.
Does this work for forex and crypto?
The arithmetic is identical: risk budget divided by risk per unit. For forex you'd convert the result into lots based on pip value, and for crypto the answer is just a fractional coin quantity. The core calculation doesn't change.