liminfoPatent Classification Reference
Free web tool: Patent Classification Reference
About Patent Classification Reference
The IPC Patent Classification Reference is a free, searchable browser tool covering all 8 sections of the International Patent Classification (IPC) system — from Section A (Human Necessities) through Section H (Electricity) — along with their major subclass codes. The IPC is the globally standardized system used by patent offices in over 100 countries to classify inventions by their technical subject matter.
Patent attorneys, patent agents, inventors, IP researchers, technology analysts, and academics use IPC codes daily to search prior art, draft patent claims, conduct freedom-to-operate analyses, and identify technology trends across patent databases such as Espacenet, Google Patents, and KIPRIS. This reference tool lets you quickly look up section codes and their meanings without navigating complex patent office documentation.
The tool presents the IPC hierarchy in two levels: sections (A through H) with their broad technology domains, and subclasses (three-character codes like A61 or G06) with descriptive labels. Sections expand on click to reveal their subclasses. A live search bar instantly filters across both sections and subclasses by code or keyword, making it easy to find the right classification area in seconds.
Key Features
- Complete coverage of all 8 IPC sections (A–H): Human Necessities, Performing Operations, Chemistry, Textiles, Fixed Constructions, Mechanical Engineering, Physics, and Electricity
- Subclass codes for 47 major IPC subclasses with full English descriptions (e.g., A61 Medical Science, G06 Computing, H04 Electric Communication)
- Instant keyword and code search that filters sections and subclasses simultaneously as you type
- Expandable section cards — click any section to reveal all its subclasses, or collapse to browse the high-level overview
- Auto-expand behavior when a search query matches subclasses within a section, so results are always visible
- Monospace code formatting for IPC codes to distinguish them clearly from descriptive labels
- 100% client-side with useMemo filtering — no server requests, instant search results
- Dark mode support and fully responsive layout for quick lookups on any device
Frequently Asked Questions
What is the International Patent Classification (IPC)?
The IPC is a hierarchical classification system administered by the World Intellectual Property Organization (WIPO) that divides all technical fields into eight sections (A–H), which are further subdivided into classes, subclasses, groups, and subgroups. It is used by patent offices worldwide to categorize patent documents, enabling structured searches of prior art.
What are the 8 IPC sections?
The 8 IPC sections are: A (Human Necessities — agriculture, food, clothing, furniture, medicine, sports), B (Performing Operations; Transporting — processes, metal working, vehicles, packaging), C (Chemistry; Metallurgy), D (Textiles; Paper), E (Fixed Constructions — roads, buildings, mining), F (Mechanical Engineering; Lighting; Heating — engines, refrigeration), G (Physics — measuring, optics, computing, signalling), and H (Electricity — electric elements, power generation, communications).
How do I read an IPC code like A61K or G06F?
An IPC code is read left to right. The first letter is the section (A = Human Necessities). The next two digits form the class (A61 = Medical or Veterinary Science). An additional letter indicates the subclass (A61K = Preparations for Medical, Dental, or Toilet Purposes). Groups and subgroups add further numeric detail (A61K 31/00). This tool covers sections and subclasses (three-character codes).
How is this tool useful for patent searching?
When searching for prior art in patent databases like Espacenet, Google Patents, or KIPRIS, filtering by IPC code narrows results to a specific technology domain, dramatically reducing noise. For example, searching G06F covers computing hardware patents, while A61B covers medical diagnostic instruments. This reference helps you identify the right IPC codes before you run your search.
What is the difference between IPC and CPC classifications?
The IPC is the international standard maintained by WIPO with about 70,000 classification entries. The CPC (Cooperative Patent Classification) is a joint extension of the IPC developed by the European Patent Office (EPO) and the US Patent and Trademark Office (USPTO) with over 250,000 entries at a finer level of granularity. The CPC is a superset of the IPC — every CPC code maps to an IPC code, but not vice versa.
How often is the IPC updated?
The IPC is updated annually by WIPO's IPC Committee of Experts. New subgroups are added to reflect emerging technologies, and existing entries are revised or merged as fields evolve. The current version is IPC-2024. This reference tool covers the main sections and subclasses, which are stable across versions.
Which patent databases use IPC codes?
IPC codes are used by virtually all major patent databases: Espacenet (European Patent Office), KIPRIS (Korean Intellectual Property Rights Information Service), J-PlatPat (Japan Patent Office), Google Patents, Lens.org, and the USPTO Patent Full-Text Database. Most allow you to filter search results by IPC section, class, or subclass.
Can I search for a technology area I am unfamiliar with?
Yes. Type a keyword into the search box to filter sections and subclasses by their English descriptions. For example, searching "medical" surfaces A61 (Medical or Veterinary Science), while "computing" finds G06 (Computing; Calculating; Counting). The search works across both section titles and subclass labels simultaneously.