ICD-10 Code Browser

What ICD-10-CM Is and Why It Matters

ICD-10-CM (International Classification of Diseases, Tenth Revision, Clinical Modification) is the diagnosis coding system used across the United States for reporting conditions on healthcare claims, mortality and morbidity statistics, quality measurement, and clinical research. Maintained jointly by the Centers for Medicare & Medicaid Services (CMS) and the National Center for Health Statistics (NCHS), it is updated every federal fiscal year, with changes taking effect on October 1. The FY2026 release contains more than 70,000 billable codes — a level of granularity that lets a single code capture not just a diagnosis but its laterality, encounter type, severity, and anatomical site.

How a Code Is Built

An ICD-10-CM code is three to seven characters long. The first character is always a letter; the second is always a digit; the rest can be letters or digits. The first three characters form the category (for example E11, "Type 2 diabetes mellitus"). Characters four through six add etiology, anatomical site, and severity. A seventh character, when required, conveys information such as the episode of care — A for an initial encounter, D for a subsequent encounter, and S for a sequela. When a code needs a seventh character but has fewer than six, the placeholder X fills the empty positions (for example T36.0X1A).

Billable vs. Non-Billable Codes

Not every entry in ICD-10-CM can be submitted on a claim. Three-character categories and intermediate subcategories often act as headers — they organize the classification but are not specific enough to bill. A code is billable (also called a "valid for submission" code) only when it is a complete leaf in the hierarchy and no further specificity is required. For example, E11 ("Type 2 diabetes mellitus") is a non-billable header, while E11.9 ("Type 2 diabetes mellitus without complications") is billable. Submitting a header code instead of its most specific child is one of the most common causes of claim denials, which is why this browser labels every result clearly.

Chapters, Blocks, and the Tabular List

The classification is organized into 22 chapters, each covering a body system or category of conditions — Chapter 9 for the circulatory system (I00–I99), Chapter 19 for injury and poisoning (S00–T88), Chapter 21 for factors influencing health status (Z00–Z99), and so on. Within each chapter, codes are grouped into blocks (also called sections), such as I20–I25 for ischemic heart disease. This chapter → block → category → code structure is the Tabular List, and navigating it is how coders move from a general body system to a precise diagnosis.

Includes and Excludes Notes

Instructional notes are essential to correct coding. Includes and inclusion terms list conditions that the code covers. An Excludes1 note is a true exclusion — "not coded here" — meaning the two codes can never be reported together because the conditions are mutually exclusive (for example a congenital versus an acquired form). An Excludes2 note means "not included here": the excluded condition is separate, but a patient may legitimately have both, so both codes can be reported when appropriate. Misreading Excludes1 as Excludes2 (or vice versa) is a frequent source of coding errors, and this tool surfaces both note types directly on the result card.

Using ICD-10-CM Responsibly

Accurate diagnosis coding depends on the official ICD-10-CM Guidelines for Coding and Reporting, the documentation in the patient's record, and payer-specific policies. A lookup tool — including this one — is a fast reference, not a substitute for those sources or for a certified encoder. Always confirm the code against the official release for the date of service, apply the relevant guideline chapters, and follow your organization's compliance process before a code reaches a claim.