Effective Spread Calculator

Understanding transaction costs in prediction markets is critical for profitability. The Effective Spread measures the true cost of trading by comparing your execution price to the mid-market price.

Calculate Your Costs

Fills

Fees (Optional)

Effective Spread (Gross) -
Quoted Half Spread -
Effective Half Spread -
Execution Price (VWAP) -
Cost (One-way, All-in) -
Cost (Round-trip, All-in) -

Latest Guides

Realized Spread vs Effective Spread: Two Similar Metrics, Different Use

Effective spread measures execution cost at trade time. Realized spread measures cost after the market moves. This guide explains both, why they differ, and what each metric tells you in prediction markets.

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What to Log for Clean Cost Metrics: Trade Journal Template

If you do not log the right fields, you cannot measure effective spread, slippage, or all in cost correctly. This guide gives a practical logging template for prediction market trading and research.

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Fee Math: Per Contract vs Percent Fees and How to Convert

Fees are quoted in different formats. This guide shows how to convert per contract fees and percent fees into comparable units, and how to add fees into all in cost and minimum edge calculations.

Read Guide →