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Position Size Calculator

Estimate shares or units from a USD risk budget and USD entry/stop prices per unit. Inputs are manual examples, not market quotes. This tool does not convert futures contracts, forex lots or currencies. Calculation runs in your browser.

For USD-priced shares or units with no contract multiplier, estimated units = (USD account equity x risk percent / 100) / absolute(entry - stop). It assumes a fill at the stop price and excludes costs; it does not guarantee a loss limit.

Risk inputs

Account equity (USD)

Risk per trade (%)

Entry price (USD/unit)

Stop price (USD/unit)

units = (account × risk percent / 100) / |entry − stop|

Your size

Dollars at risk—

Risk per unit—

Estimated size (units)—

Notional value (USD)—

Position as % of account—

Type your numbers to size the position.

How it works

What this calculator does

This estimate applies when a $1 price move changes the value of one share or unit by $1. Enter account equity in USD, risk as a percentage (enter 1 for 1%), and entry and stop in USD per share/unit. Default values are an example, not a trade recommendation or a live quote.

The formula

risk budget = account × (risk percent / 100)
units = risk budget / |entry − stop|
notional value = units × entry

The stop distance is the assumed dollar loss per share/unit. Notional value is not margin required. For a long position the stop is normally below entry; for a short it is above entry. This tool uses the absolute distance and does not validate a broker order.

Worked example

With a $25,000 account, a 1% risk budget is $250. If you enter at $50 and place a stop at $48, the per-share risk is $2. Then 250 / 2 = 125 shares. Your position is 125 × 50 = $6,250, but your loss if stopped out is still just $250 — the risk, not the position value, is what you fixed.

Read the result before placing an order

The displayed quantity is rounded for readability. Recalculate at your broker's permitted increment and round down, not up: a raw result of 33.333 shares permits 33 whole shares, with $99 of price risk at a $3 stop distance. Fractional trading, minimum size and available buying power depend on your broker.

What it deliberately does not do

It assumes your stop fills at the stated price; gaps, slippage and fees can increase the loss. There is no contract multiplier, pip/tick value, currency conversion, margin rule or portfolio correlation input. Do not read its unit result as futures contracts or forex lots. Verify product specifications separately; this is educational arithmetic, not a guaranteed loss limit or investment advice.

Frequently asked questions

How do I calculate position size from risk?

Divide your dollar risk budget by the per-unit distance between entry and stop: (account × risk%) / |entry − stop|. A wider stop means a smaller position for the same risk.

What percentage of my account should I risk per trade?

No fixed percentage makes a trade safe. The example 1% is an input, not a recommendation. Choose a budget with your total exposure, potential drawdown and ability to absorb losses in mind.

Why does a wider stop give me a smaller position?

Because risk is fixed. If each share can lose more before the stop, you must hold fewer shares to keep the total loss inside the same dollar budget.

Does position size depend on my stop-loss?

Yes — the stop distance is the denominator. Without a defined stop there's no per-unit risk to divide by, so the calculation can't run.

Does this guarantee I'll only lose the amount I set?

No. It assumes the stop fills exactly. Overnight gaps or fast markets can fill worse than your stop, so treat the figure as an estimate, not a guarantee.

Related calculators

Information and education only, not investment, trading, tax or financial advice. Manual calculations run in your browser without a broker connection. Fees, slippage and gaps can make losses exceed the estimate. Shared URLs contain selected inputs; optional email registration is saved separately. See the privacy details.