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.