Position Sizing for Beginners: How the 1% Risk Rule Works (With a Calculator Formula)

Last updated: 2026-10-28

Short answer: The 1% rule means risking at most 1% of your account on a single trade. To get position size, divide the amount you're willing to lose by the distance between entry and stop-loss. Include fees and slippage, round down to what the platform allows, and never size a trade by feel.

Ask a new trader how much they risk per trade and you'll usually hear "€100" or "half my account" or "depends how confident I am". None of those is an answer.

The question that matters isn't which trade you take. It's how big. Two traders can take the exact same entry and exit — one survives a losing streak, the other blows the account. The difference is position sizing.

This article explains the "1% rule", the formula behind it, and how to put it in a spreadsheet so you never size a trade by feel again.

Risk note: Not financial advice. Trading involves substantial risk and you can lose money, including more than you expect if you use leverage. Position sizing manages risk; it doesn't eliminate it.

What does the 1% rule actually mean?

The 1% rule says: on any single trade, don't risk more than 1% of your account.

"Risk" here doesn't mean the size of the position. It means how much you lose if your stop-loss is hit.

• Account: €2,000
• 1% risk = €20

That doesn't mean you buy €20 worth of something. It means you size the position so that if price hits your stop, you lose about €20. The position itself can be much bigger than €20.

Some traders use 0.5%, some 2%. The exact number is your call. The point is to pick a fixed number in advance and apply it every time.

Why does a small fixed percentage matter?

Losing streaks are normal

Even a reasonable strategy can have several losers in a row. Look at what different risk levels do after 10 consecutive losses (pure maths, compounded on the remaining balance):

At 1% you're bruised. At 10% you've lost about two-thirds of the account.

Recovery is asymmetric

After a 50% drawdown you need a 100% gain just to get back to where you started. Small risk per trade keeps drawdowns in a range you can actually recover from — and keeps you calm enough to follow your plan.

How do you calculate position size?

You need three inputs:

1. Account size (A)
2. Risk % (R)
3. Stop distance — the difference between your entry price and your stop-loss price (D), per unit (per share, per coin, etc.)

Risk amount = A × R Position size (units) = Risk amount ÷ D

Then check: Position value = units × entry price. If that's more than you can or want to hold, the trade doesn't fit — reduce size or skip it.

Illustrative worked example (stock or spot crypto)

Made-up numbers to show the calculation:

• Account: €2,000
• Risk: 1% → €20
• Entry: €50.00
• Stop-loss: €48.00
• Stop distance: €2.00 per unit

Position size = €20 ÷ €2.00 = 10 units Position value = 10 × €50 = €500

If the stop is hit, you lose 10 × €2 = €20 (plus fees and possible slippage). That's 1% of the account, even though the position is worth €500.

Same account, wider stop

• Entry €50, stop €45 → distance €5
• Position size = €20 ÷ €5 = 4 units (€200 position)

The wider the stop, the smaller the position. Risk stays the same. This is the key idea: you don't choose a size and then a stop. You choose the stop based on the chart, then the size follows from the maths.

Don't forget fees, slippage and gaps

The formula assumes you exit exactly at your stop. Real life is messier:

• Fees: add round-trip fees to the risk calculation, or lower your risk % slightly to leave room.
• Slippage: in fast markets, your stop may fill at a worse price.
• Gaps: prices can open far beyond your stop (overnight, over weekends, around news). A stop-loss order is not a guaranteed exit price.

A practical approach: calculate size with your planned risk, then estimate the "bad case" loss including fees and some slippage, and make sure you're still comfortable with it.

What about leverage?

Leverage lets you open a position bigger than your cash. It doesn't change the formula — position size is still risk amount ÷ stop distance. What changes is how easy it is to open a position that's far too big, and the risk of liquidation or margin calls if price moves against you.

For beginners: if you can't explain how your broker or exchange calculates margin, liquidation price and funding/overnight costs, don't use leverage yet.

Build the calculator in a spreadsheet

Make a small tab called "Position size":

Round B7 down to what your platform allows (whole shares, minimum lot, coin decimals). Rounding up quietly increases your risk.

A pre-trade checklist

Before every order:

• Stop-loss level chosen from the chart/plan, not from "how much I want to make"
• Position size from the calculator, rounded down
• Bad-case loss (with fees/slippage) still acceptable
• Total open risk across all trades within your limit (e.g. no more than a few % at once)
• Trade logged in your journal

What are the common position sizing mistakes?

• Moving the stop further away after entry "to give it room". That silently multiplies your risk.
• Risking more after a loss to "win it back".
• Ignoring correlation: three positions in assets that move together are closer to one big position.
• Using the 1% on the wrong number — e.g. on the position value instead of the stop-loss loss.

Where to go next

Position sizing is where the Phoebus Lab Trading course on risk management and the trading journal begins: risk on paper and a journal template before the first trade. The course has three tracks (Forex, binary options and crypto trading), each with its own modules, and no signals. It is education; trading can lose money.

Related reading: How to Keep a Trading Journal: Template, Key Metrics and a Weekly Review · A risk unit is a rule. “I feel it” is how accounts die

— TICK