Position Size Calculator
Position size is the number of shares or units you trade so that a stopped-out trade costs a fixed percent of your account. It comes from one division: the dollars you are willing to risk, divided by the distance between your entry and your stop.
Free position size calculator for stocks and forex. Enter your account size, risk percent, entry, and stop loss below and get your share size instantly. Plain risk math, no chart upload, no AI involved.
Last updated
Position Size Calculator
Manual risk math: enter your own numbers, no chart upload needed
Enter account size, risk %, entry, and stop to see your position size.
The formula
How position size is calculated
Position size = (Account size × Risk %) ÷ Risk per share
Risk per share = |Entry price − Stop loss price|
The dollar amount you are willing to risk (account size × risk %) gets divided by how much you lose per share if the stop is hit. The result is floored down to a whole share count so your actual risk never exceeds the percentage you chose.
Worked example
Account size: $25,000. Risk: 1% ($250). Entry: $50.00. Stop: $48.50.
Risk per share = |$50.00 − $48.50| = $1.50. Position size = $250 ÷ $1.50 = 166.6, floored to 166 shares.
Dollar risk by account size and risk tier
| Risk % | $25k account | $50k account | $100k account |
|---|---|---|---|
| 0.5% | $125 | $250 | $500 |
| 1% | $250 | $500 | $1,000 |
| 2% | $500 | $1,000 | $2,000 |
This is the dollar amount at risk on a single trade at each tier. How many shares that buys depends on your stop distance.
Common position-sizing mistakes
- —Sizing off gut feel instead of the actual dollar distance between entry and stop.
- —Risking the same share count on every trade regardless of how wide the stop is.
- —Ignoring pip value or lot-size conversion on forex pairs, so the real risk is different than intended.
- —Increasing size after a loss to "get it back": sizing should follow a fixed rule, not a losing streak.
- —Sizing each trade independently when several open positions are correlated, so real combined risk is higher than any single trade shows.
- —Forgetting that this is pre-trade planning math: slippage, fees, and gaps can still move the realized risk away from the plan.
You did the sizing math. Want AI to grade the setup too?
This calculator only answers how many shares. It does not know if the setup itself is any good. Upload a chart screenshot and SnapPChart grades the setup quality A+ to F, with an entry, stop, and targets, in seconds.
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Related free tools and guides
- GuidePosition sizing from risk per tradeThe 1% rule math, a worked table across account sizes, and why a fixed share count quietly randomizes your losses.
- Free toolBreakeven Win Rate CalculatorFree breakeven win rate calculator: enter your reward:risk ratio (or entry, stop, target) to see the minimum win rate to break even, plus expectancy.
- Free toolFutures Position Size CalculatorFree futures position size calculator: pick ES, NQ, MES, MNQ, CL or GC, enter your risk and stop, and get the contract count with tick and point values.
- Free toolProp Firm Drawdown CalculatorFree prop firm drawdown calculator: enter your balance, peak, and max loss limit to see your liquidation level, buffer left, and losses until you fail.
- Free toolRisk Reward Ratio CalculatorFree risk reward ratio calculator: enter entry, stop and target for a long or short trade to get the R:R as 1 : X, the R-multiple, and your breakeven win rate.
FAQ
Position sizing questions
What is position sizing?
Position sizing is deciding how many shares (or units, for forex) to trade so that a fixed percentage of your account is at risk if your stop loss is hit. It answers 'how many shares', not 'is this a good setup', which is a separate decision.
How much should I risk per trade?
Most risk frameworks land between 0.5% and 2% of account size per trade. A common starting point is 1%: on a $25,000 account, that is $250 of risk on any single trade, sized by how far your stop is from your entry.
Does this calculator work for forex and futures?
It works for forex when you toggle the forex option, which switches the risk-per-unit display to pip-scale pricing without a currency prefix. It is built around price-per-share risk, so it does not account for futures contract multipliers or margin. For futures and index CFDs, use the contract math in the next answer.
How do I size a futures or index CFD position?
Same idea, with point value standing in for share price. Contracts = dollar risk ÷ (stop distance in points × point value per contract). ES is $50 per point, NQ is $20, MES is $5, and MNQ is $2. Risking $250 on MES with a 10-point stop is 250 ÷ (10 × 5) = 5 contracts. Index CFDs like NAS100 or SPX500 have no standard point value, since it depends on your broker's contract size, so check that number before you do the math.
What's the difference between position size and lot size?
Position size is the general concept: how much of an instrument to hold. Lot size is the forex-specific unit (a standard lot is 100,000 units of the base currency). This calculator outputs raw share/unit counts; convert to lots yourself if your broker quotes in lot sizes.
Should I round the share count down or up?
Down. This calculator floors the result so your actual dollar risk never exceeds your target; rounding up would let a trade risk slightly more than the percentage you chose.
Can this account for multiple open positions at once?
No. It sizes one trade at a time, in isolation. If you already have open, correlated positions, their combined risk is on you to track; the calculator has no visibility into your other trades or broker balance.
Benjamin Loh
Founder & Developer at SnapPChart
I build AI-powered tools for traders. I created SnapPChart to help day traders analyze chart patterns faster using computer vision and machine learning. Learn more · Follow on X
This calculator is for planning purposes only and is not financial advice. It computes share size from the numbers you enter. It does not know your broker's fees, slippage, margin requirements, or your other open positions. Trading involves risk of loss.