How Can a Trader Calculate the Effective Spread for a Filled Order?

The effective spread for a filled order is calculated as: 2 × | Execution Price – Mid-Price |. The mid-price is the average of the best bid and best offer at the time the order was submitted.

This calculation measures the total cost of the trade relative to the prevailing market price, including any slippage or price impact incurred during execution.

In Financial Derivatives, What Is the Difference between a Quoted Spread and an Effective Spread?
What Is the Practical Implication of a “Wide Mid-Price” in an Illiquid Options Market?
What Is the Concept of the ‘National Best Bid and Offer’ (NBBO)?
What Is the Relationship between the Bid-Offer Spread and the ‘Cost of Immediacy’ in Derivatives Trading?
What Is the “Mid-Point Peg” Order Type Commonly Used in Dark Pools and How Does It Function?
Explain How the Effective Spread Is Used as a Metric for Broker Execution Quality
What Is the “Mid-Price” of an Option and Why Is It Often Used as a Benchmark?
Why Is the Effective Spread Calculated as “Twice the Difference”?

Glossar