ICD-9 to ICD-10 Crosswalks

The ICD-9-CM (I-9)  to ICD-10-CM (I-10),  and I-10 to I-9 crosswalk tools are based on the Centers for Medicare and Medicaid (CMS) General Equivalency Mapping (GEMS) documents.  Per the CMS Gems guide: “The I-10 and I-9 GEMs are used to facilitate linking between the diagnosis codes in I-9 volume 1 and the new I-10 code set. The GEMs are the raw material from which providers, health information vendors and payers can derive specific applied mappings to meet their needs.”  

However, CMS cautions that “GEMs are not crosswalks. They are reference mappings, to help the user navigate the complexity of translating meaning from one code set to the other. GEMs are tools to help the user understand, analyze, and make distinctions that manage the complexity, and to derive their own applied mappings if that is the goal. The GEMs are more complex than a simple one-to-one crosswalk, but ultimately more useful. They reflect the relative complexity of the code sets clearly so that it can be managed effectively, rather than masking it in an oversimplified way.” 


During this period prior to the ICD-10 implementation, for those who want to start familiarizing themselves with ICD-10 codes, the following free online sites contain information on how to translate I-9 codes into I-10 codes and I-10 codes into I-9.  Keep in mind that both GEMS and crosswalk tools are meant to be used in conjunction with the ICD publications in order to ensure that you select the most appropriate code for the particular situation.

The American Academy of Professional Coders

Alkaline Software ICD Tool

The inclusion or mention of any website, product, procedure, or method of practice in this article does not constitute endorsement by the College or Congress.


Donna Tyler
Manager, Coding Education

Keisha Sutton
Coding Specialist