Position Size Calculator

Work out the correct position size for a trade when your stop-loss is set at a specific price — a swing low, a moving average, a key support or resistance level — rather than a fixed pip distance. The calculator measures the distance from entry to stop for you, applies your risk rule, and returns a position size in your account currency.

How to use it

1. Account currency. Pick the currency your trading account is denominated in. All output figures are converted into this currency.
2. Account balance. Enter your current balance, or the balance you want to size from for a hypothetical scenario.
3. Risk mode. Choose % of balance if you follow a percentage risk rule, or Fixed amount if you cap risk at a specific cash figure.
4. Risk percentage or risk amount. Enter the value that matches your selected mode.
5. Instrument. Search and select the instrument you’re trading. This determines pip definition, quote currency and contract size.
6. Entry price. The price at which you plan to enter the trade.
7. Stop-loss price. The price at which the trade would be invalidated. Direction (long or short) is inferred from whether the stop is below or above entry.
8. Hit Calculate position size. The calculator returns the position size in lots, the equivalent in units, the stop distance in pips and the cash risk in your account currency.

A worked example

Imagine a $5,000 USD account with a 2% risk rule, and you want to short EUR/USD from 1.0850 with a stop above a recent swing high at 1.0900.

• Account balance: 5,000 USD
• Risk: 2% → 100 USD at risk
• Instrument: EUR/USD
• Entry price: 1.0850
• Stop-loss price: 1.0900 → 50 pips of stop distance

The calculator converts the price-based stop into a pip distance, works out the pip value in your account currency, and divides your 100 USD risk by the cost of a 50-pip move. The output is the position size that caps the worst-case loss at, or just below, 100 USD.

When to use it

• Structure-based trading. When your stop is anchored to a chart level — a recent swing point, an order block, a moving average — you already know the price, not a tidy pip number. Drop the levels in and let the calculator handle the distance.
• Indices, commodities and stock CFDs. Thinking in pips on the S&P 500 or gold is unnatural; thinking in prices is. This calculator lets you size positions in those instruments the way you actually look at them.
• Variable stop distances. If your stop distance changes from trade to trade (which it should, if you respect structure rather than forcing a fixed-pip stop), you need a tool that recalculates every time. This is that tool.
• Trade planning. Sketch out an entry and a stop on the chart, type both into the calculator, and see whether the position size and pip distance line up with a sensible target. If the size feels too small, your stop is probably too wide for your risk rule.

The formula

Show the maths

The calculator works in two steps:

1. Stop distance in pips = |Entry price − Stop-loss price| ÷ Pip size

2. Position size = Risk amount ÷ (Stop distance in pips × Pip value per lot in account currency)

Where:

• Pip size is 0.01 for JPY-quoted pairs and 0.0001 for most other forex pairs. Indices and CFDs use their own minimum increments.
• Risk amount = account balance × risk percentage, or the fixed cash figure you entered.
• Pip value per lot is converted into your account currency using the live FX rate.

Common mistakes

• Stop too tight for the structure. Don’t shrink your stop just to allow a bigger size — if the stop sits inside normal noise, it will get hit and your position size becomes irrelevant.
• Wrong direction implied. A buy with the stop above entry, or a sell with the stop below entry, doesn’t make sense. Double-check that your stop is on the protective side of your entry.
• Stale entry price. Markets move. If you enter your inputs ten minutes before pulling the trigger and the price has shifted, redo the calculation so the size still matches reality.
• Forgetting broker lot increments. The calculator returns an ideal size; brokers usually round to 0.01 lots. Round down rather than up to stay inside your risk rule.

Related calculators

• Lot Size Calculator — same goal, but for traders who think in pip distances rather than price levels.
• Profit / Loss Calculator — once you have the position size, project the cash outcome at your target.
• Margin Calculator — check how much margin the planned position will tie up before placing the trade.

These calculators are for educational purposes only. Trading leveraged products carries a high level of risk and may not be suitable for all investors.