Position sizing basics

Position sizing basics

In the last lesson, you learned to risk a fixed percentage of your account per trade — not a fixed lot size. This lesson covers exactly how to calculate the position size that achieves that fixed dollar risk, no matter where your stop loss is.

The three numbers you always need

1. Account risk amount — your account size × your risk percentage (e.g. $10,000 × 1% = $100)
2. Stop loss distance — how far your entry is from your stop loss, in pips or points
3. Pip/point value — how much one pip or point is worth per unit of position size, which depends on the instrument you're trading

The formula

Position size = Account risk amount ÷ (Stop loss distance × Pip value per unit)

This formula always produces a position size where, if your stop loss is hit, you lose exactly your intended risk amount — no more, no less.

Why stop distance changes your position size

Look at the diagram above: both trades risk the exact same $100. The trade on the left has a stop loss 20 pips away, so it can only be 0.5 lots. The trade on the right has a stop loss just 5 pips away, so it can be 2 lots — four times the size for the same dollar risk.

The tighter your stop loss, the larger your position size can be for the same dollar risk. The wider your stop loss, the smaller your position size needs to be.

This is a critical insight: a "small" looking stop loss in pips is not automatically "low risk." It's only low risk relative to the position size you're trading. A trader who doesn't adjust their position size to their stop distance is taking wildly inconsistent risk from trade to trade without realizing it.

A simple worked example

Account: $10,000. Risk: 1% = $100. Stop loss distance: 50 pips. Pip value: $10 per standard lot.

Position size = $100 ÷ (50 pips × $10) = $100 ÷ $500 = 0.2 lots

If this trade hits the stop loss, the loss is exactly $100 — exactly 1% of the account, regardless of how far away the stop was.

The mistake most beginners make

New traders often pick a position size first (like "I'll trade 1 lot because that feels normal") and then place a stop loss wherever the chart suggests, without ever calculating what percentage of their account that combination actually risks. This backwards approach means their real risk varies wildly and unpredictably from trade to trade — sometimes risking 0.5%, sometimes risking 8%, without ever intending to.

The right order of operations

1. Decide your strategy's entry and stop loss location based on the chart (using everything you've learned about structure, support/resistance)
2. Calculate the stop distance
3. Calculate the position size that makes that stop distance equal your fixed risk percentage
4. Only then enter the trade

Position sizing is the bridge between "I have a good entry idea" and "I am actually managing risk correctly." Skipping it means everything else you've learned in this curriculum is undermined by inconsistent, accidental risk-taking.

• Position size = Account risk amount ÷ (Stop loss distance × pip value per unit)
• A tighter stop loss allows a larger position size for the same dollar risk, and vice versa
• Never pick position size first and stop loss second — calculate stop distance from the chart first, then size the position to match your risk percentage
• Consistent risk per trade only happens when position size is calculated, not guessed