Position size calculator for swing trading: how many shares to buy
This free calculator turns your account size, risk per trade, entry and stop into a share count. It shows the core rule of risk management: the stop decides the size.
By the Momentum & Growth team · Last updated October 12, 2026 · About us
See the Beginners Kit: $37Position size calculator
Enter your numbers. Nothing is stored or sent anywhere.
How the calculation works
- Dollar risk = account size × risk percent.
- Risk per share = entry price minus stop price.
- Shares = dollar risk divided by risk per share, rounded down.
Example with made-up numbers: a $10,000 account risking 1% has $100 of risk. With an entry at $50 and a stop at $47.50, the risk per share is $2.50, so the size is 40 shares, a $2,000 position.
Choosing your inputs
Risk percent
Many traders keep risk per trade small, often 1% or less, so a losing streak does not damage the account badly. This is a common guideline, not advice.
Stop price
Place the stop where the trade idea is clearly wrong, such as below support. Do not move it further away just to buy more shares.
Entry price
Use the price you actually plan to pay. Gaps and slippage can make real losses bigger than planned.
Limits of any calculator
- A stop is not guaranteed. Stocks can gap past it overnight, especially around earnings.
- Commissions and fees are not included.
- A large position relative to your account adds concentration risk even when the dollar risk is small.
Worked examples
| Account | Risk % | Entry | Stop | Shares | Position value |
|---|---|---|---|---|---|
| $5,000 | 1% | $20.00 | $19.00 | 50 | $1,000 |
| $10,000 | 0.5% | $80.00 | $76.00 | 12 | $960 |
| $25,000 | 1% | $150.00 | $144.00 | 41 | $6,150 |
These numbers are illustrations of the math only.
Common sizing mistakes
- Choosing the share count first and the stop second.
- Moving the stop to make a bigger position fit.
- Ignoring that several positions can fall together.
- Forgetting that gaps can make losses larger than planned.
Why fixed-percent risk works
Risking a fixed percent of the account means position sizes shrink after losses and grow after gains. That slows down drawdowns during losing streaks. For example, ten losses in a row at 1% each leave about 90% of the account, while ten losses at 10% each would leave about 35%.
These figures are simple math, not a prediction.
Frequently asked questions
What is position sizing?
Deciding how many shares to buy so that, if your stop is hit, you lose only the amount you planned.
Why round the shares down?
Rounding down keeps the loss at or below your planned risk.
Is this calculator investment advice?
No. It is a math tool for education. You make your own decisions.
Related guides and comparisons
- What is swing trading?
- Swing trading journal
- How to choose a swing trading course
- Best swing trading courses 2026
- How to swing trade for beginners
- Swing trading strategy for beginners
- Swing trading vs day trading
- Swing trading under $25,000
- How to find stocks to swing trade
- Free vs paid swing trading courses
- Cheapest way to learn stock trading
- Are trading courses worth it?
Want a plan you can follow at your own pace?
The Momentum & Growth Trading System is a one-time, self-paced swing trading course. Start with the $37 Beginners Kit, or get all three kits for $97.
Educational content only, not investment advice. Trading involves risk of loss, and no course can promise results.
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