How is this calculated?

Correct contracts equal intended dollar risk divided by premium per share times 100, rounded down. Mistaken contracts equal intended dollar risk divided by premium per share alone, rounded down. The tool then shows the actual dollar risk each contract count would represent once the 100-share multiplier is correctly applied.

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How much extra risk would I take on if I sized this options trade without accounting for the 100-share contract multiplier?

Q: How much extra risk would I take on if I sized this options trade without accounting for the 100-share contract multiplier?

Calculates the correct number of option contracts for an intended dollar risk amount, accounting for the standard 100-share contract multiplier, and shows the actual dollar risk that would result from mistakenly ignoring that multiplier.

Every habit in this library exists because I paid tuition for the mistake first.

Jason Parker, Founder of Trading Habits

Enter Your Intended Trade

This checks the arithmetic behind your order size, not the trade itself.

Your Result

Fill in the fields on the left and click Check to see the correct contract count and the cost of the multiplier mistake.

How this is calculated

A standard equity option contract represents 100 shares. The total cost of one contract is the quoted premium per share multiplied by 100, not the quoted premium alone.
The correct contract count divides your intended dollar risk by premium times 100. The mistaken count divides intended risk by premium alone, which is off by a factor of 100 on the per-contract cost.
This assumes a standard 100-share contract. Adjusted contracts, which exist after certain corporate actions like stock splits or spinoffs, can represent a different number of shares, so confirm contract terms for any option you're not certain is standard.
This checks arithmetic only. It does not evaluate whether the trade itself, the strike, or the expiration make sense.

Risk & liability disclaimer: This calculator produces a mathematical estimate based on the numbers you enter. It is not financial advice and does not guarantee any trading outcome. Trading involves risk of loss, and past position sizing decisions do not predict future results. Trading Habits is not a broker-dealer, registered investment adviser, or tax professional, and is not affiliated with any broker, exchange, or data provider. We do not guarantee this tool is error-free or suitable for your situation - always verify results independently and consult a licensed professional before making any trading or financial decision. You could lose some or all of the capital you trade with.

How much extra risk would I take on if I sized this options trade without accounting for the 100-share contract multiplier?

Enter Your Intended Trade

Your Result

How this is calculated

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