Free Position Size Calculator Online — Stocks, Forex, Crypto

Position sizing is the single most important skill in trading. It does not matter how good your entries are if one bad trade wipes out ten winning trades. This calculator tells you exactly how many shares to buy based on your account, your risk tolerance, and your stop loss.

The Position Sizing Formula

Every professional trader uses the same formula. It is simple, but most beginners skip it and pay for it later:

Position Size = (Account Size x Risk %) / (Entry Price - Stop Loss Price)

That is it. Three inputs, one output. The output tells you the maximum number of shares (or units) you should buy to keep your risk within your defined limits.

Step-by-Step Example

1. Account size: $25,000
2. Risk per trade: 2% = $500 maximum loss
3. Entry price: $85.00 (where you plan to buy)
4. Stop loss: $80.00 (where you exit if wrong)
5. Risk per share: $85 - $80 = $5.00
6. Position size: $500 / $5 = 100 shares
7. Total position value: 100 x $85 = $8,500 (34% of account)

If the trade hits your stop loss, you lose exactly $500 — which is 2% of your account. Not 10%, not 20%, not "whatever happens." Controlled risk.

Why Position Sizing Matters More Than Your Entry

Traders spend hundreds of hours studying chart patterns, indicators, and setups. They spend almost no time on position sizing. This is backwards.

• A great entry with bad sizing can still blow up your account. If you buy too many shares and the stock gaps through your stop loss, the loss is catastrophic
• A mediocre entry with proper sizing keeps you in the game. Even a 40% win rate is profitable if your winners are bigger than your losers and your position sizes are consistent
• Consistency beats prediction. You cannot predict the market. You can control how much you lose when you are wrong

Position Sizing Across Markets

Market	Entry Example	Stop Loss	Risk Per Unit	How to Read Output
Stocks	$150.00/share	$142.00	$8.00/share	Output = number of shares to buy
Forex (EUR/USD)	1.0850	1.0800	0.0050 (50 pips)	Output = units. Divide by 100K for standard lots
Crypto (BTC)	$65,000	$63,500	$1,500	Output = fraction of 1 BTC to buy
Futures (ES)	5,200	5,190	10 points ($500)	Output = contracts (adjust for point value)

Common Risk Percentages

Risk %	Who Uses It	Max Consecutive Losses Before 20% Drawdown
0.5%	Conservative traders, large accounts	40 losses
1%	Professional standard, recommended default	22 losses
2%	Experienced traders, smaller accounts	11 losses
3%	Aggressive traders	7 losses
5%	Gambling, not trading	4 losses

The math is clear: lower risk percentage means more room for error. If you are still learning, use 0.5% or 1%.

Mistakes That Position Sizing Prevents

• The "all-in" trade: Putting 50% of your account in one position because you are "sure" it will work. It will not always work
• Inconsistent sizing: Buying 500 shares of a $10 stock and 500 shares of a $200 stock. The dollar exposure is completely different
• Widening stops without adjusting size: If you move your stop loss further away, your position size must decrease proportionally
• Ignoring gaps: Stocks can gap past your stop loss overnight. Proper sizing means even a gap-through loss does not destroy your account

Related Trading Calculators

• Position Size Calculator — how many shares to buy
• Stock Profit Calculator — calculate P&L on any trade
• Compound Interest Calculator — long-term growth projections
• Risk/Reward Calculator — evaluate trade setups
• Percentage Calculator — quick percentage math