Position size calculator

Your numbers

The equity you trade with, in dollars.

The share of the account lost if the stop is hit. Many traders use 0.5–2%.

The price you plan to buy at, or to sell short at.

Where the trade idea is wrong: below the entry for a long, above it for a short.

Results

Shares
100
Dollar risk at the stop
$250.00
Position value
$5,000.00
Position as % of account
20.0%
Risk per share (1R)
$2.50
Direction
Long

An educational tool: results leave out commissions, slippage and gaps. Nothing you enter is sent or saved. Not investment advice.

How to use it

  1. Enter the account size and the percentage of it you are prepared to lose on this one trade.
  2. Choose the stop from the chart first, beyond the level that proves the idea wrong, then enter the entry and the stop.
  3. Read the share count. The dollar risk is what the trade costs if the stop fills at its price.
  4. Check the position value. A very close stop produces a large position; if it is a large share of the account, consider a lower risk percentage or a wider, more meaningful stop.

The formula

Risk budget = account × risk %

Risk per share = |entry − stop|

Shares = risk budget ÷ risk per share, rounded down to whole shares.

Position value = shares × entry. Commissions, slippage and gaps through the stop are not included, so a real loss can be larger than the dollar risk shown.

Worked example

Illustrative numbers: a $25,000 account risking 1% has a risk budget of $250. Buying at $50 with a stop at $47.50 risks $2.50 per share, so the calculator returns 100 shares (250 ÷ 2.50).

The position is worth $5,000, or 20% of the account. If the stop fills at $47.50 the loss is $250, which is 1R. Move the stop up to $48.75 and the same $250 buys 200 shares worth $10,000: a closer stop means a larger position, not a smaller risk.

Questions

How do I calculate position size for a stock trade?

Multiply the account size by the risk percentage to get the dollar risk, divide it by the distance between the entry and the stop, and round down. A $25,000 account risking 1% with a $2.50 stop distance gives 100 shares.

What percentage of the account should I risk per trade?

It is a personal decision rather than a rule. Many traders use 0.5% to 2% so that a long losing streak leaves most of the account intact: ten losses in a row at 1% each cost about 9.6% of the account.

Does the calculator work for short trades?

Yes. Enter a stop above the entry and the trade is treated as a short; the share count, the dollar risk and the position value are worked out the same way.

Why can the loss be larger than the dollar risk?

A stop order becomes a market order once it is triggered, so a fast market or a gap through the stop can fill it at a worse price. Commissions and fees are not included either.

Is anything I enter saved?

No. The calculation runs in your browser; nothing is sent to Clear Tape or stored.

Related guides

Other calculators

From the calculation to the record

Save the entry, stop and target as a plan before the trade, then log the fills. The journal works out R, expectancy and drawdown from your own trades, and its AI score grades how closely each trade followed the plan. A free account is all it takes.