Favorites

Investing & Trading

Position Size Calculator

Estimate how many units to trade so the planned stop-loss matches your risk limit.

App view

Inputs

Results

Result Enter values to calculate.
Your result explanation will appear here.

Useful next checks

  • Check the inputs before relying on the result.
  • Try a second scenario to compare outcomes.
  • Read the guide below for context.

Intro

Use this position size calculator to estimate how many units to trade from account size, risk percentage, entry price, and stop-loss price.

What this calculator does

The calculator converts account risk into a money amount, compares it with the distance from entry to stop, and rounds the position size down to whole units.

How it works

Risk amount is account size x risk percentage. Risk per unit is the absolute difference between entry price and stop-loss price. Position size is risk amount / risk per unit, rounded down.

Example calculation

With a 10,000 account, 1% risk, 50 entry, and 47 stop, the risk amount is 100. Risk per unit is 3, so the rounded position size is 33 units.

How to use the result

Use the result as a planning estimate before placing a trade. Actual losses can differ because of price gaps, spreads, fees, slippage, partial fills, and stop execution. This is not financial advice.

Assumptions and limitations

  • The calculator assumes whole-unit sizing.
  • It does not include commission, spread, leverage, or margin rules.
  • It uses the absolute entry-to-stop distance, so it can be used for long or short planning.

FAQs

  • If the stop is very close to entry, the calculated size can be large.
  • If the stop equals entry, the trade has no defined risk distance and cannot be calculated.
  • Use the risk/reward calculator to compare the target with the same stop.

Related calculators

Frequently asked questions

Why is the size rounded down?

The calculator rounds whole-unit position size down so the estimated loss does not exceed the selected risk amount.

Can this be used for short trades?

Yes. The risk per unit is based on the absolute distance between entry and stop.

Does this guarantee the actual loss?

No. Slippage, gaps, spreads, and fees can change real trade outcomes.