Position Size Calculator
The exact number of units to trade so that hitting your stop costs precisely the amount you decided to risk — no more, no less. Enter your balance, risk percentage, entry and stop, and see the position size, dollar risk, leverage and what happens if the stop is hit.
OPTIONAL · TARGET FOR R:R CONTEXT
The diagram below shows the same dollar risk spread across three different stop distances. A tighter stop means a bigger position for the same risk — and a bigger position means more leverage. The final bar shows what the account looks like if the stop is hit.
Position sizing is the practice of deciding how much to trade, not what to trade. It is the single most important risk-management decision you make, and it is the one most retail traders skip. Two traders with identical entries and identical stops can have wildly different outcomes, purely because they sized their positions differently.
The formula in one sentence
Divide the dollar amount you are willing to lose by the distance from entry to stop. The answer is the number of units. If you are willing to lose $100 and your stop is $5 away, you buy 20 units. If your stop is $1 away, you buy 100 units. The dollar risk is the same in both cases — only the size changes.
Every loss costs the same
The whole point of position sizing is to make every loss identical in dollar terms. If you risk 1% per trade, then every stop-out costs exactly 1% — whether the stop is 0.5% away or 5% away from entry. This removes the emotional volatility of "big" and "small" losses and makes your equity curve much smoother.
Tighter stops need more leverage
A tighter stop produces a bigger position for the same dollar risk — and a bigger position requires more capital or more leverage. A stop 0.1% away from entry on a 1% risk budget requires 10× leverage. That is fine if the stop is genuinely far enough from the noise; it is fatal if the stop is inside the normal daily range and gets hit on the first wiggle.
The 1% rule of thumb
Most professional traders risk between 0.5% and 2% per trade. At 1% risk, a losing streak of ten trades in a row costs about 9.6% of the account — painful but survivable. At 5% risk, the same streak costs 40% — and you now need a 67% gain just to get back to breakeven. The math of recovery is brutal, and it is the reason small risk per trade is not optional.
The recovery math — why risk per trade matters more than win rate
| Risk per trade | 10 losses in a row | Gain needed to recover | What it means |
|---|
Worked examples
Balance = $10,000 · Risk = 1% → Dollar risk = $100
Entry = 100 · Stop = 95 → Risk per unit = $5
Position size = $100 ÷ $5 = 20 units
Position value = 20 × 100 = $2,000 · Leverage = 0.20×
Same account and risk. Entry = 100 · Stop = 98 → Risk per unit = $2
Position size = $100 ÷ $2 = 50 units
Position value = 50 × 100 = $5,000 · Leverage = 0.50×
Same dollar risk. Bigger position. More leverage. Higher chance of being stopped out.
Entry = 100 · Stop = 90 → Risk per unit = $10
Position size = $100 ÷ $10 = 10 units
Position value = 10 × 100 = $1,000 · Leverage = 0.10×
Same dollar risk. Smaller position. Lower leverage. Lower chance of being stopped out by noise.
Balance = $10,000 · Risk = 5% → Dollar risk = $500
Entry = 100 · Stop = 90 → Position size = $500 ÷ $10 = 50 units
If the trade stops out: account is now $9,500.
If five trades stop out in a row: account is $7,737 — a 22.6% drawdown.
To recover from $7,737 back to $10,000 requires a 29.2% gain.
Frequently asked questions
Because a bad pick costs a fixed, small amount when you size correctly, but a good pick sized too large can wipe out months of progress in a single trade. A trader with a 40% win rate who risks 1% per trade will build a smooth equity curve over hundreds of trades. A trader with the same 40% win rate who risks 10% per trade will go bust on the first five-loss streak — which will happen within the first fifty trades. The edge comes from the strategy; the survival comes from the sizing.
Most professionals use 0.5% to 2%. Beginners should start at 0.5% or 1% until they have at least 100 trades of real data showing a positive expectancy. There is no universally correct number, but the guiding principle is: size so that a normal losing streak does not force you to change your strategy or your behaviour. If a ten-loss streak would make you stop trading or start revenge-trading, you are risking too much. As a rule of thumb, 2% is aggressive, 1% is standard, and 0.5% is conservative.
Because position sizing is about keeping the dollar loss constant. If your dollar risk is $100 and your stop is $5 away, you can buy 20 units. If your stop is $1 away, you can buy 100 units — because each unit only loses $1 before the stop triggers, so you need five times as many units to lose the same $100. The trade-off is real: the tighter stop produces a bigger position, which produces more leverage, which produces a bigger percentage swing in your account when the price moves. Tighter stops are not free; they just shift the risk from "loss per unit" to "position size and leverage."
From the stop, always. The stop is the event you are certain to face at some point — even the best strategies lose 40% to 60% of their trades. The target is the event you hope for. Sizing from the stop means every losing trade costs the same predetermined amount, which makes your equity curve stable and your drawdowns predictable. Sizing from the target would mean the size depends on how optimistic you are about the outcome, which is exactly the wrong way to think about risk.
Leverage is a tool, not a goal. The position size calculator tells you how many units to trade for your dollar risk — if that position value exceeds your account balance, you need leverage to open it. In practice, the leverage required is simply position value ÷ account balance, and it should be a result of the stop distance, not a target you aim for. The danger sign is when you are choosing a stop distance because it gives you a certain leverage. That is backwards. Set the stop where the trade is proven wrong, then let the calculator tell you the size and the resulting leverage.
The 1% rule says you should never risk more than 1% of your account on a single trade. It emerged from the turtle trading experiments in the 1980s and has been a standard rule of thumb ever since. It is not sacred — many successful traders use 0.5% or 2% — but it is a reasonable starting point, particularly for beginners. The spirit of the rule is more important than the exact number: risk a small enough fraction that no single trade or losing streak can meaningfully impair your capital or your ability to keep trading.
No — the dollar risk stays the same, but the position size changes with each trade's stop distance. That is the whole point of the formula. A trade with a wide stop gets a small position; a trade with a tight stop gets a large one. As long as the dollar risk is constant, the percentage loss from a stop-out is constant too, and that is what stabilises the equity curve. Only the dollar risk percentage stays fixed from trade to trade.
Position sizing controls how much you lose per trade. The risk-reward ratio controls how much you make when you win. Together they define expectancy: (win rate × R:R × dollar risk) − (loss rate × dollar risk). The two are complementary tools: R:R is used when deciding whether to take a trade, and position sizing is used when deciding how much to trade it. A high R:R with a bad position size will still lose money; a good position size with a bad R:R will at best break even. Both are needed.
How to Use This Calculator
Four numbers determine the size of every position you take: your balance, the percentage you are willing to risk, your entry price and your stop. Enter them and the calculator does the rest.
1. Pick the direction
Long if you are buying, short if you are selling. The stop must sit below entry for a long, above entry for a short — the calculator will flag it if you have them the wrong way around.
2. Enter your balance and risk percentage
Use the current equity figure from your broker. The risk percentage is how much of that balance you are willing to lose on this trade. Start at 1% or less if you are new.
3. Enter entry and stop
Use the prices from your trade plan. The stop should be at a price where the trade is genuinely proven wrong — not just close enough to give you a nice R:R. Distance from entry to stop is the only thing that determines the position size.
4. Read the result
The result card shows the number of units to trade, the dollar risk, the position value and the leverage required. If the leverage figure is higher than your platform allows, widen the stop or reduce the risk percentage.
5. Add a target for context
The target is optional. Position size does not depend on it — but if you enter a target, the calculator will show the reward if it is hit and the R:R ratio, giving you a complete picture of the trade.
6. Watch the leverage warning
If the position value exceeds your account balance by more than a small factor, the calculator warns you. This usually means the stop is too tight relative to your risk budget, and you may want to widen it.
What This Tool Offers
Everything you need to translate a trade idea into a correctly sized position.
Exact position size
The number of units to trade so that hitting the stop costs exactly your predetermined dollar risk. No rounding up, no guessing.
Full risk breakdown
Dollar risk, position value, leverage required, and the percentage of the account at risk — all in one place.
Comparison diagram
A visual showing how the same dollar risk produces different position sizes and different leverage as the stop distance changes. Helps build intuition for the trade-off.
Risk presets
Quick buttons for the common risk levels — 0.25%, 0.5%, 1%, 1.5%, 2%, 3% and 5% — so you can see the effect of risk percentage without typing.
Step-by-step working
Every calculation shown line by line, so you can check the math or learn the formula. Includes optional R:R context when a target is entered.
Reference and recovery table
A table showing the drawdown from ten losses in a row at every risk level from 0.5% to 10%, with the gain required to recover. This is the arithmetic that makes small risk per trade non-negotiable.
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| Position Size | Position size | coins |
| Account Balance | Total trading account balance | currency |
| Risk % | Percentage of account willing to risk on this trade | |
| Entry Price | Planned entry price | currency |
| Stop-Loss Price | Stop-loss price | currency |
What it means
Position sizing is a critical aspect of risk management. This formula calculates the position size (in units) based on the account balance, the percentage of capital to risk (usually 1‑2%), and the distance between entry and stop‑loss. It ensures that a losing trade only risks a predetermined fraction of the account. This is used to prevent large drawdowns and to preserve capital over the long term. Understanding position sizing is essential for professional trading and for avoiding emotional decisions. It is a key component of any trading system.
Worked example
Position Size Calculator – Two Detailed Examples
Real‑World| Parameter | Value |
|---|---|
| Account Balance | $10,000 |
| Risk % | 1.0% |
| Entry Price | $60,000 |
| Stop‑Loss Price | $58,000 |
| Parameter | Value |
|---|---|
| Account Balance | $5,000 |
| Risk % | 2.0% |
| Entry | $3,000 |
| Stop‑Loss | $2,850 |
Common mistakes
- Account balance: Use the total trading capital (including margin if used).
- Risk %: The percentage of account you are willing to risk per trade (e.g., 0.02 for 2%).
- Entry and stop‑loss prices: Use the same units.
- Position size: In units of the base currency – may need to convert to quote currency.
Applications
Position size calculator (risk management) determines the amount to trade based on the account balance, the risk percentage per trade, and the distance to the stop‑loss. This helps traders manage risk by ensuring that no single trade can cause a significant loss. By calculating the position size, traders can control their exposure and protect their capital. This formula is a key component of risk management systems used by both retail and institutional traders. It also assists in scaling positions and in adjusting size based on market volatility. Understanding position sizing is fundamental to long‑term trading success.
- Determining trade size to limit risk per trade
- Implementing a consistent risk management strategy
- Scaling positions based on account equity
- Protecting capital from large drawdowns
- Educational tool for traders
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