Position Size Calculator

A position size calculator works out how many lots to trade so that, if your stop loss is hit, you lose only the amount you chose to risk. Lots = money at risk ÷ (stop distance in pips × pip value per lot).

KCM Academy Editorial Team
Editorial policy
Last updated 29 October 2026
Position size (rounded down to 0.01 lot)
—

Money at risk = balance × risk % ÷ 100. Pip value per lot = contract size × pip size, converted at your rate. Lots = money at risk ÷ (stop pips × pip value per lot).

How do you calculate position size?

Position size in lots = money at risk ÷ (stop distance in pips × pip value per lot). The money at risk is the share of your balance you choose to risk, and the pip value per lot comes from the contract size and pip size. It takes three steps:

  1. Money at risk = account balance × risk per trade (%) ÷ 100.
  2. Pip value per lot = contract size × pip size, converted into your account currency if the price is quoted in a different currency.
  3. Lots = money at risk ÷ (stop distance in pips × pip value per lot).

The calculator rounds the result down to the nearest 0.01 lot, so the size it shows never risks more than the amount you entered.

What is a worked example of position sizing?

With a $5,000 account, 1% risk and a 25-pip stop on EURUSD, the position size is 0.20 lots, which risks exactly $50. The money at risk is $5,000 × 1 ÷ 100 = $50, and one pip on 1 lot is worth $10, so $50 ÷ (25 × $10) = 0.20.

StepCalculationResult
Money at risk$5,000 × 1 ÷ 100$50
Pip value per lot100,000 × 0.0001$10 per pip
Position size$50 ÷ (25 × $10)0.20 lots

Check: at 0.20 lots each pip is worth $2, so a 25-pip stop costs 25 × $2 = $50, the amount you chose.

The same trade in an account held in another currency works the same way once the pip value is converted at the exchange rate you enter. MT5 converts every result into your account currency at the live rate; the country guides show local examples.

The idea behind this calculation is covered in the position sizing lesson of Module 5, Risk Management, and pip value in the lots, pips and pip value lesson of Module 2. Lot sizes themselves are explained in our guide to forex lot sizes.

What does each input mean?

The calculator needs your balance, the percentage you want to risk, your stop distance in pips and the instrument's contract size, pip size and quote currency. An exchange rate field appears when the price is in another currency. Where to put the stop itself is covered in the stop loss and take profit lesson.

What are the assumptions and limits?

The result is a lot size rounded down to 0.01, so it never risks more than you entered, using generic contract and pip sizes. Check the symbol's own values in MetaTrader 5. The stop can fill past its level in a fast market, so the realised loss can differ from the plan.

Frequently asked questions

Is a lot size calculator the same as a position size calculator?

Yes. Position size is measured in lots, so both names describe the same calculation: how many lots fit the amount you choose to risk and the distance to your stop.

What percentage of my account should I risk per trade?

This academy does not recommend a figure. The calculator shows the arithmetic for whatever percentage you enter, so you can see what a given risk means in money before you decide.

Why does the calculator round the lot size down?

So the position never risks more than you entered. Rounding 0.207 lots up to 0.21 would make the loss at the stop slightly larger than your chosen amount; rounding down to 0.20 keeps it at or below it.

What does it mean if the result is below 0.01 lots?

It means even the smallest usual position size would lose more than your chosen amount if the stop is hit. The calculator shows this as below 0.01 rather than rounding up.

Does the position size include spread and commission?

No. The calculation covers the price distance to your stop only. Spread, commission and swap are extra costs, so the total loss on a stopped-out trade can be a little larger than the money at risk shown.

Sources

Practise what you learned

Open an account to use MetaTrader 5. Start on a demo account before risking real money.

Open Account