Position Size Calculator

Size a trade from account risk, entry price, stop distance, and fees, then review exposure, stop loss, and optional reward-to-risk.

Size the trade from the loss you are willing to take at the stop Position sizing starts with risk budget, not conviction. This calculator works backward from account size, risk tolerance, entry, and stop so the planned loss stays inside the chosen budget before the order is placed.

Direction

Asset type

Display currency

Switch displayed monetary values without changing the position-size arithmetic.

Result

62

Shares to trade at $48.00 with a stop at $44.00 while keeping the planned loss near $250.00.

Risk budget is the limiting factor The stop distance and round-trip fees are the main constraint, so the recommended size keeps total stop loss near the chosen risk budget.
Position value
$2,976.00
Risk at stop
$248.00
Stop distance
$4.00 (8.33%)
Account exposure
11.9%

Risk budget used

99.2%

Unused risk budget: $2.00 after fees.

Target scenario

$744.00

Net profit at $60.00 with an estimated reward-to-risk ratio of 3.

How to use the result

The recommended size assumes the stop will be honored and the trade can be exited near the stop price. Real slippage, overnight gaps, spreads, borrowing costs, and liquidity can produce a larger loss than this estimate.

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Trade Risk

Position size calculator guide: shares or units from account risk, stop distance, and fees

A position size calculator starts with the amount you are willing to lose if the stop is hit and works backward to the number of shares or units that fits that loss budget. That makes it a risk-control tool first and a trade-planning tool second. The goal is not to maximize size, but to keep one trade from doing disproportionate damage to the account.

Why position size starts with risk budget

Many traders think first about the chart pattern, conviction level, or upside target. Position sizing flips that order. The first question becomes how much of the account can be put at risk on one idea without undermining the larger plan if the trade fails.

That is why the calculator begins with account size and a risk percentage. A stop price then translates that risk budget into a per-unit loss. Once that number is known, the trade size can be scaled so the planned stop loss fits inside the chosen limit.

Core maths behind the recommended size

Per-unit risk is the distance between entry and stop. For a long trade, the stop must sit below the entry. For a short trade, the stop must sit above the entry. The risk budget is the account size multiplied by the chosen risk percentage, then reduced by any round-trip fees you want included.

The calculator also checks whether the account can actually fund the risk-based size. If the capital needed at the entry price is larger than the account balance, the recommendation is capped by available cash rather than by the stop-distance risk budget.

Risk budget = Account size x Risk percentage

Sets the maximum loss the trader is willing to tolerate on the setup before fees.

Risk-based units = (Risk budget - Fees) / Per-unit stop distance

Converts the risk budget into a maximum number of shares or units using the stop distance.

Position value = Units to trade x Entry price

Checks how much capital the recommended size would actually commit at the entry.

How target price and reward-to-risk fit in

A target price does not decide the position size in this calculator. The size is determined by the stop-distance loss budget. The target is used afterward to estimate potential net profit and the approximate reward-to-risk ratio if the position reaches that target and the round-trip fees remain unchanged.

That order matters because an attractive upside target cannot repair a position that is already too large for the stop distance. Good reward-to-risk does not excuse poor size discipline.

What this estimate does not cover

Real execution can be worse than the stop price because of slippage, overnight gaps, bid-ask spread widening, or illiquidity. Those risks are especially important in fast-moving or thinly traded markets and can make the real loss larger than the planned loss.

Use the output as a sizing baseline, not as a guarantee. If the market or instrument can gap violently, many traders deliberately size below the theoretical maximum shown by a stop-distance model.

Further reading

Frequently asked questions

Why is stop distance more important than confidence in the trade?

Because the stop distance determines how much money is lost per share or unit if the setup fails. Confidence is subjective; per-unit risk is arithmetic. Position size should be anchored to the arithmetic.

 Why does the calculator sometimes say the account is cash-limited?

Because the risk-based size may require more capital at the entry price than the account actually has available. In that case, the maximum cash-funded size is smaller than the maximum risk-based size.

 Does this guarantee my maximum loss?

No. It assumes the stop can be executed near the stop price. Real losses can be larger if the market gaps, liquidity is poor, or the stop is not honored exactly.

 Should I include fees in position sizing?

Usually yes, especially for smaller accounts, frequent trading, or products with wider spreads and higher costs. Fees consume part of the risk budget even before market movement is considered.

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