Position Size Calculator (Free, Built for Active Traders)
A position size calculator tells you exactly how many shares to buy so a single losing trade can't blow up your account. Enter your account size, the percent you're willing to risk, your entry price, and your stop-loss price. We do the math: you get a share count, your dollar risk, and your risk-reward ratio if you also enter a target.
Results
Position size
50
Round down, never buy more shares than the formula allows.
Total dollar risk
$250.00
If your stop hits, this is your loss.
Position value
$5,000.00
Total capital deployed in this trade.
Risk per share
$5.00
Entry minus stop, the distance you're risking on each share.
Risk / reward ratio
2.00 : 1
Reward per $1 risked. Most pros only take trades with R:R >= 2:1.
Results update live as you change inputs. This calculator runs entirely in your browser — your numbers are never sent to a server.
Worked example
You have a $25,000 account and you're willing to risk 1% ($250) on this trade. You plan to buy at $100 and exit at $95 if the trade fails, that's $5 of risk per share. So you buy $250 / $5 = 50 shares. Your total position value is $5,000 (20% of your account, but only 1% is at risk). If price hits $110 your reward is $10/share = $500, giving a 2:1 R:R.
Frequently asked questions
What is a position size calculator?
A position size calculator tells you how many shares to buy on a trade so that if your stop-loss hits, you only lose a pre-set percentage of your account (typically 1-2%). It takes the math out of risk management, you input account size, risk %, entry, and stop, and it returns your exact share count.
What's a good risk percent per trade?
Most professional and serious retail traders risk 0.5% to 2% of their account per trade. Risking 1% means you'd need a 100-trade losing streak to blow up your account, which is statistically improbable. Higher than 2% per trade dramatically raises your risk of ruin even with a 60% win rate.
Should I include commissions and slippage?
For exact precision, yes, subtract round-trip commissions and expected slippage from your max loss before dividing. For most retail trades on commission-free brokers (Robinhood, Fidelity, Schwab), the impact is small enough to ignore. For options or futures, factor them in explicitly.
How is position size different from position value?
Position size = number of shares. Position value = shares × entry price (total capital tied up). Risk = the small portion of that value you'd actually lose if your stop hits. A 50-share position at $100 entry has $5,000 of position value but might only have $250 of risk if your stop is $5 below entry.
Can I use this for forex or futures?
Not directly, forex uses pip values and lot sizing, futures use contract values and tick multipliers. This calculator is built for stocks and ETFs. We'll publish dedicated forex and futures position-size calculators on Insigtrade next.
What does R-multiple or 1R mean?
1R is the amount you're risking on a trade (your max loss). A 2R winner means you made twice your risk. Position sizing makes 1R consistent across trades, every trade risks the same dollar amount, so a 3R win after a 1R loss leaves you up 2R, regardless of whether the trade was a $5 stock or a $200 stock.