Position Size Calculator
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.
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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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, convert your point value to a dollar risk manually before entering it here.
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.
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.