A stop loss calculator converts your risk tolerance into a concrete price level and position size. Rather than guessing where to place a stop or how many shares to buy, this tool ensures every trade risks exactly the dollar amount you intend. Enter your account size, risk percentage, and entry price, and the calculator above returns the optimal stop price and corresponding position size.
How to Use
| Input | What to Enter | Example |
|---|---|---|
| Account Size | Your total trading account balance | $50,000 |
| Risk Per Trade | Percentage of account to risk on this trade | 1% |
| Entry Price | Price at which you plan to enter | $220.00 |
| Stop Loss Method | Choose percentage, ATR-based, or fixed price | Percentage |
| Stop Loss Value | The percentage distance, ATR multiplier, or exact stop price | 3% |
The calculator outputs your stop loss price, the number of shares to trade, and the exact dollar amount at risk. If the position size seems too large for the stock’s liquidity, consider tightening the stop or reducing risk percentage.
Formula Explained
Stop Distance = Entry Price - Stop Loss Price
Position Size = (Account Size × Risk %) / Stop Distance
Stop Distance is the per-share loss if the trade hits your stop. For a $220 entry with a 3% stop, the distance is $6.60 ($220 × 0.03). This number anchors the entire calculation — a wider stop means fewer shares, and a tighter stop means more shares.
Account Size × Risk % gives the total dollar amount you can lose on the trade. A $50,000 account risking 1% yields $500 of risk capital. This is the ceiling for the trade’s maximum loss, and it stays fixed regardless of the stock price or stop distance.
Position Size is the result of dividing dollar risk by stop distance. With $500 of risk and a $6.60 stop distance, the position size is 75 shares ($500 / $6.60 = 75.75, rounded down). Rounding down ensures actual risk stays at or below the target.
Example Calculations
Scenario 1: Percentage-Based Stop on a Swing Trade
- Account: $50,000
- Risk: 1% ($500)
- Entry: MSFT at $220.00
- Stop: 3% below entry = $213.40
- Stop Distance: $6.60
- Result: 75 shares ($16,500 position)
A 3% stop works well for multi-day swing trades in large-cap stocks where daily moves of 1-2% are normal. The $500 risk represents a controlled loss that preserves capital across a series of trades.
Scenario 2: ATR-Based Stop on a Volatile Stock
- Account: $30,000
- Risk: 2% ($600)
- Entry: COIN at $95.00
- Stop: 2× ATR ($2.50 ATR) = $90.00
- Stop Distance: $5.00
- Result: 120 shares ($11,400 position)
Using a 2× ATR multiplier gives the trade room to breathe through normal volatility. The ATR position size calculator can automate this process when you have the ATR value from your charting platform.
Scenario 3: Support-Based Stop on a Large-Cap
- Account: $100,000
- Risk: 0.5% ($500)
- Entry: NFLX at $415.00
- Stop: Below support at $408.00
- Stop Distance: $7.00
- Result: 71 shares ($29,465 position)
Placing stops just below identified support levels gives the trade a logical invalidation point. If support breaks, the trade thesis is wrong, and the stop executes at a predefined loss.
When to Use a Stop Loss Calculator
- Before every trade entry — calculate the stop and position size together so risk is defined before capital is committed
- When switching timeframes — day trades need tighter stops than swing trades, which changes position size significantly
- After a drawdown — as account size shrinks, position sizes must shrink proportionally to maintain consistent percentage risk
- When trading volatile assets — stocks with high ATR values need wider stops, making position sizing critical to avoid oversized losses
- During portfolio heat reviews — checking that combined open-position risk stays within total portfolio limits
Related Tools
- Position Size Calculator — calculates shares to trade when you already know your stop price, working as the inverse of this tool
- ATR Position Size Calculator — specializes in volatility-adjusted position sizing using Average True Range data
- Risk-Reward Calculator — evaluates whether a trade’s potential profit justifies the stop loss distance before entry
Frequently Asked Questions
How do you calculate where to place a stop loss?
Stop placement depends on the method: percentage-based stops use a fixed percentage below entry, ATR-based stops use a multiple of average true range, and support-based stops sit just below a key price level. The best method depends on the asset’s volatility and your trading timeframe.
What is a good stop loss percentage for day trading?
Most day traders use stop losses between 0.5% and 2% below their entry price, depending on the stock’s volatility. The stop percentage should reflect the asset’s normal price fluctuation to avoid being stopped out by random noise while still protecting capital.
Should stop loss determine position size or vice versa?
Stop loss placement should always drive position size. First identify the correct stop level based on price structure or volatility, then use a position size calculator to determine how many shares to buy. Sizing positions first leads to arbitrary stop placement and inconsistent risk.
What is an ATR-based stop loss?
An ATR-based stop loss uses the Average True Range indicator to set stop distance. A common approach is placing the stop 1.5 to 3 ATR units below the entry price. This method adapts to current volatility — wider stops in choppy markets, tighter stops in calm ones — producing more consistent results than fixed-percentage stops.
How much should you risk per trade with a stop loss?
Professional traders typically risk 0.5% to 2% of their account per trade. Risking 1% is the most common guideline. At 1% risk, a trader can sustain 20 consecutive losses before drawing down 20%. Use the risk of ruin calculator to model how your risk percentage affects long-term survival probability.
