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Options Position Size Calculator

Suggested contracts equals account risk dollars divided by maximum loss per contract, rounded down.

Expiration scenarios

Solution

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Educational estimate only, not financial advice. Results exclude commissions, taxes, slippage, dividends, assignment risk, margin, and broker-specific rules. Verify before trading options.

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Options Position Size Formula

Position size is based on account risk budget divided by max loss per contract.

Worked Examples

Load these examples to compare common options position size payoff outcomes.

POSITION SIZE

Size contracts from max loss

A trader wants to keep a defined-risk spread within 2% account risk.

  • Enter the manual prices and assumptions.
  • Review the calculated risk, reward, and break-even metrics.
  • Compare the chart with the highlighted scenario.

Result: the calculator updates the scenario metrics and chart from those inputs.

Real fills, fees, and broker margin rules are not modeled.

How It Works

This calculator sizes an options trade from account risk budget and max loss per contract.

Example Problem

Enter account value, risk percentage, max loss per contract, and planned contracts.

  1. Convert risk percent into dollars.
  2. Divide by max loss per contract.
  3. Round down to whole contracts.
  4. Compare planned risk with budget.

Broker margin and buying power can be stricter than max-loss sizing.

Key Concepts

Defined-risk position sizing starts with the maximum acceptable loss.

Applications

  • Sizing spreads.
  • Checking planned contracts.
  • Keeping risk consistent across trades.

Common Mistakes

  • Sizing from premium received instead of max loss.
  • Rounding up contracts.
  • Ignoring correlated positions.

Frequently Asked Questions

What does the Options Position Size Calculator calculate?

It calculates the selected options result from manual inputs, without requiring live stock or option quotes.

Does this calculator need live market data?

No. Enter the prices, premiums, volatility, days, or Greeks yourself. The calculator uses those manual inputs only.

Are commissions, taxes, margin interest, and assignment fees included?

No. The result excludes commissions, fees, taxes, borrow costs, slippage, and broker-specific margin rules.

Why can real trading results differ?

Real option prices can change with implied volatility, liquidity, dividends, early assignment, and execution prices.

Reference:

Standard options payoff, probability, and risk-management formulas.

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