Stop Loss Calculator

A stop loss order is a pre-set instruction that automatically closes a trading position when the price of a security falls to a specified level. It is one of the most fundamental risk management tools available to traders and investors, designed to cap losses on any single trade before they spiral out of control.

When you enter a trade, you face two unknowns: whether the trade will go in your favor, and by how much it might move against you. A stop loss order answers the second question definitively — it defines the exact dollar amount or percentage of your account you are willing to lose if the trade moves the wrong way. Without one, a single bad trade can wipe out weeks or months of gains.

Stop loss orders are available on virtually every trading platform for stocks, ETFs, futures, forex, and cryptocurrencies. They execute automatically, which removes the emotional decision-making that causes many traders to hold losing positions too long, hoping the market will reverse. By setting a stop loss before you enter a trade, you commit to a rational exit plan rather than reacting emotionally under pressure.

This stop loss calculator supports three calculation methods: a percentage-based stop (a fixed percentage below entry), an ATR-based stop (a multiple of the Average True Range, adapting to current market volatility), and a fixed price stop (an absolute dollar price level). Each method suits different trading styles and market conditions. The calculator also derives the correct position size from your account size and maximum risk tolerance, ensuring that if the stop is hit, your total loss never exceeds the percentage of capital you chose to risk.

The calculator uses three distinct formulas to compute the stop loss price, depending on which method you select. All three then feed into the same position sizing formula to determine how many shares you can buy while keeping your risk within limits.

Percentage Stop

The percentage stop is the simplest and most widely used method. You specify what percentage below the entry price you are willing to tolerate:

Percentage Stop Price = Entry Price × (1 − Stop%)

For example, a 5% stop on a $100 entry gives a stop price of $100 × (1 − 0.05) = $95.

ATR-Based Stop

The ATR (Average True Range) stop anchors your stop to current market volatility. A wider ATR means the market is moving more, so your stop needs to be further away to avoid being hit by normal noise:

ATR Stop Price = Entry Price − (ATR Value × ATR Multiplier)

A common setting is 2× ATR. If ATR = $2.50 and entry = $100, the stop is $100 − ($2.50 × 2) = $95.

Fixed Price Stop

You enter an absolute dollar price level directly — useful when you want to place the stop just below a key support level or a recent swing low.

Position Sizing from Risk

Once the stop price is set, the calculator computes how many shares to buy so your potential loss exactly equals your maximum risk:

Risk Per Share = |Entry Price − Stop Loss Price|

Max Risk Amount = Account Size × (Risk% / 100)

Position Size = floor(Max Risk Amount / Risk Per Share)

Position sizing is the process of determining how many shares (or contracts) to buy so that if your stop loss is hit, you lose exactly the dollar amount you planned to risk — no more. Most professional traders consider position sizing more important than entry timing, because it is the mechanism that keeps any single loss manageable relative to the total account.

The key input is your risk percentage per trade — the fraction of your account you are willing to lose on one trade. A widely cited guideline is 1–2% per trade. With a $25,000 account and a 2% risk limit, you risk at most $500 per trade regardless of which stock you buy or how wide your stop needs to be.

Once you know your maximum risk in dollars and the risk per share (entry minus stop), the position size follows directly: Position Size = floor(Max Risk / Risk Per Share). If your max risk is $500 and the risk per share is $5, you buy 100 shares. If the stop needs to be $10 away because the stock is more volatile, you buy only 50 shares — automatically reducing your exposure in volatile conditions.

The calculator also shows the position value (shares × entry price) and what percentage of your account that represents. Large positions as a percentage of account introduce concentration risk even if the stop loss percentage itself is small. Many risk managers cap individual positions at 10–20% of total account value regardless of stop distance.

The "If Stopped Out" output shows exactly how much your account shrinks if the stop fires. Repeated 2% losses are recoverable; repeated 10% losses compound against you severely. This asymmetry — the mathematics of drawdown recovery — is why professional traders are strict about capping risk per trade.

Each of the three stop loss methods in this calculator suits a different trading approach. Understanding when to use each helps you place stops that are both protective and realistic — not so tight they trigger on normal market noise, and not so wide they expose you to excessive loss.

Percentage Stop

Best for systematic or rules-based traders who want a consistent approach across all positions. A 5% stop on every trade keeps risk uniform and easy to track. The weakness is that percentage stops ignore volatility — a 5% stop on a low-volatility utility stock is very different from a 5% stop on a high-beta tech stock.

ATR-Based Stop (Volatility Stop)

The ATR stop adapts to actual market volatility. Average True Range measures the average daily price movement, so multiplying it by 1.5x–3x gives a stop that is beyond normal daily noise while still being responsive to meaningful trend breaks. This is the preferred method among professional swing and trend traders. A 2× ATR stop is a common starting point.

Fixed Price Stop

Used when you want to place a stop at a specific technical level — below a support zone, below a key moving average, or just under a recent swing low. Chart-based stops reflect market structure rather than mechanical formulas. The trade-off is that you must then back-calculate your position size rather than starting from a preset percentage.

Stop Distance Assessment

The calculator classifies stops by distance: under 3% is a "tight stop" prone to being triggered by normal volatility, 3–7% suits most swing trades, 7–15% suits position trading over weeks or months, and over 15% reflects a long-term investment stance. Tighter stops require smaller positions to keep dollar risk the same; wider stops allow fewer shares but reduce whipsaw risk.

A trailing stop moves upward as the price rises, locking in a growing portion of your profit while still giving the trade room to continue running. Unlike a fixed stop loss, a trailing stop never moves downward — it only ratchets higher as the position gains value.

This calculator shows four trailing stop scenarios for gains of +5%, +10%, +15%, and +20% from entry. For each scenario, it applies your chosen percentage stop to the new (higher) price, showing you both where the stop would sit and how much profit would be locked in if the stop fired at that level.

For example, if you entered at $100 with a 5% percentage stop and the price rises to $110 (+10%), a trailing stop would be placed at $110 × (1 − 0.05) = $104.50. If the stock then reverses and hits $104.50, you exit with a $4.50 per-share gain rather than a loss — the trailing stop converted a potential reversal into a profitable exit.

The locked profit figure shown is: (Trailing Stop Price − Entry Price) × Position Size. A positive number means you are guaranteed a profit even if stopped out; a negative number means the trailing stop has not yet risen above your breakeven entry price.

Trailing stops are especially powerful in strong trending markets where prices make a series of higher highs. They allow you to participate in extended moves without manually raising your stop each day, and they eliminate the anxiety of watching an open profit evaporate because you held too long.

A stop loss calculator is a tool; the discipline to use it consistently is what separates profitable traders from the rest. Risk management is not just about placing stops — it is a comprehensive framework for sizing positions, diversifying exposure, and preserving capital through losing streaks.

The 1% to 2% rule is the most commonly cited guideline: never risk more than 1–2% of your account on a single trade. At 2% risk per trade, you would need 50 consecutive losing trades to lose your entire account — a virtually impossible outcome if your system has any edge at all. At 10% risk per trade, just 10 losses in a row wipe you out, and a 10-trade losing streak is realistic for many systems.

Drawdown mathematics make this concrete. To recover a 10% account loss, you need approximately an 11% gain. To recover a 50% loss, you need a 100% gain. The asymmetry means losses compound against you faster than gains recover you. Keeping individual losses small is mathematically more important than having a high win rate.

Correlation risk is another dimension: if all your open positions are in the same sector or move together in a market selloff, your individual position stops do not protect you from simultaneous multi-position losses. Diversifying across uncorrelated assets reduces this risk.

Finally, slippage — the difference between your stop price and the actual execution price — matters in fast markets or illiquid securities. Stop-limit orders protect against bad fills but can result in no fill at all if prices gap through your limit. Market-order stops guarantee execution but not price. Understanding this trade-off is essential for anyone relying on stop losses as a hard risk control.