Risk per trade

Stock Position Size Calculator

Enter your account value, how much you will risk per trade, and your entry and stop prices to get the stock position size that fits your risk budget. You also see whether your maximum allocation caps it, the position weight, and reward-to-risk when you add a target. Long stock trades only, sized in whole shares, before commissions.

Free calculator

Calculate stock position size from risk

Account
%

Max allocation caps the position value as a share of the account. Use 0 for no cap.

Risk per trade
%
Prices

Long stock trades only: the stop sits below the entry.

Stock position size
100 shares
A $10,000.00 position with $500.00 at risk, 20% of the account. Set by your risk budget.
Risk-based size
100 shares
$10,000.00, 20% of the account. This limit binds.
Max allocation size
125 shares
$12,500.00 cap. Not binding.
Risk budget
$500.00
$0.00 left unused.
Reward-to-risk
3 to 1
Gain at target
$1,500.00
Risk and reward on one price scale

100 shares: each $1 move between stop and target is $100 on the position.

Target$115.00+$15.00 / share
Entry$100.00
Stop$95.00-$5.00 / share
Risk per share
$5.00
Stop move
5%
Target move
15%
Loaded security
Manual scenario

How to use the Stock Position Size Calculator

  1. Enter your account value and the most you will risk per trade, as a percentage or in dollars.
  2. Enter the entry and stop prices; loading a ticker fills the current price as the entry.
  3. Add a target price and a maximum position size to see risk/reward and any cap.

How the calculation works

The calculator converts a risk budget into a share count. For a long-position scenario, risk per share is the entry price minus the stop price. The share count is then capped by the max position percentage when the risk-based size would be too large for the account.

Formula

Risk budget = account value x risk per trade %

Risk per share = entry price - stop price

Risk-based shares = floor(risk budget / risk per share)

Max allocation shares = floor(account value x max position % / entry price)

Final shares = the smaller of the two

Risk/reward = (target - entry) / (entry - stop)

Input definitions

Account value
The portfolio or trading account value used to calculate risk budget and position weight.
Risk per trade
The maximum dollar amount or account percentage you are willing to risk in the scenario.
Entry price
The assumed buy price per share.
Stop price
The assumed exit price used to define downside risk per share.
Target price
An optional upside level used to calculate risk/reward and target gain.

Worked example

If an account is $50,000 and the risk budget is 1%, the dollar risk budget is $500. With a $100 entry and $95 stop, risk per share is $5, so the risk-based position size is 100 shares before applying any max position cap.

With a 10% maximum position, the stock can be at most $5,000 of the account, or 50 shares at $100. The allocation cap binds, so the final size is 50 shares and only $250 of the $500 risk budget is used.

If the target is $115, the scenario has $15 of potential gain per share versus $5 of risk per share, or a 3-to-1 risk/reward ratio. That ratio is based entirely on the prices entered.

What the results mean

  • The share count is the most you can buy so that hitting the stop loses no more than your risk budget.
  • Unused risk budget appears when rounding down to whole shares or the position cap leaves part of the budget unspent.

Assumptions and limitations

  • Long positions only: the stop must be below the entry.
  • The stop is assumed to fill at its price. A stock can gap through the stop overnight or on news, so the actual loss can exceed the planned risk.
  • Whole shares only, and commissions are not included.

Stock Position Size Calculator FAQ

What does a stock position size calculator do?

A stock position size calculator estimates how many shares fit a risk budget by comparing the entry price with the stop price and limiting the result by account size and optional max position weight.

Is this position size a trading recommendation?

No. The result is arithmetic based on your inputs. It does not decide whether the trade is attractive, whether the stop is appropriate, or whether the target is likely.

How is risk per share calculated?

Risk per share equals entry price minus stop price for long-position scenarios. If the stop is not below the entry, the calculator cannot produce a positive risk-based share count.

Why can max position percent reduce the share count?

The max position setting caps position value as a percentage of account value, so a risk-based share count can be reduced when it would make the position too large.