What is a .BRD File? Eagle PCB File Format Explained

If you’ve downloaded an open-source hardware project or received PCB design files from a colleague, chances are you’ve encountered a .BRD file. This file format is fundamental to PCB design workflows, yet many engineers—especially those new to the field—aren’t sure what it contains or how to work with it.

I remember my first encounter with a .BRD file. A client sent me an Eagle design that needed modifications, and I spent an hour figuring out how to open it properly. That experience taught me the importance of understanding PCB file formats, and it’s why I’m writing this comprehensive guide to help you avoid the same confusion.

What is a .BRD File?

A .BRD file is a printed circuit board layout file created by Autodesk EAGLE (Easily Applicable Graphical Layout Editor). The file contains the complete physical design of a PCB, including component placement, copper traces, pads, vias, board outline, and layer definitions. The “.brd” extension stands for “board,” directly referencing its purpose as a board layout file.

While EAGLE is the most common application associated with .BRD files, other PCB design tools also use this extension. Cadence Allegro, KiCad (in older versions), and some legacy tools create their own versions of .BRD files. However, these formats are not interchangeable—an Allegro .BRD file won’t open in EAGLE, and vice versa.

The .BRD file works in conjunction with the .SCH (schematic) file in EAGLE projects. While the schematic defines the electrical connections between components, the .BRD file translates that into a physical layout that can be manufactured. Changes in one file directly affect the other through EAGLE’s forward and back-annotation features.

History of the Eagle .BRD Format

EAGLE was originally developed by CadSoft Computer GmbH, a German company founded in 1988. The software quickly gained popularity among hobbyists and professionals due to its affordable licensing and capable feature set. Autodesk acquired CadSoft in 2016, and EAGLE is now part of the Autodesk family of design tools.

The .BRD file format has evolved significantly over EAGLE’s history:

The transition to XML format in version 6.0 was significant. Earlier .BRD files used a proprietary binary format that required EAGLE to interpret. The XML format is human-readable—you can open a modern .BRD file in any text editor and see the design data structured in readable tags and attributes.

What Information Does a .BRD File Contain?

An Eagle .BRD file stores comprehensive PCB design information organized in a hierarchical structure:

Board Geometry and Outline

The file defines the physical boundaries of the PCB, including the board outline, cutouts, and milling paths. This information is typically stored on Layer 20 (Dimension) in EAGLE.

Layer Definitions

EAGLE uses a numbered layer system, and the .BRD file contains data for each layer:

Component Placement

The .BRD file stores each component’s position (X, Y coordinates), rotation angle, and which side of the board it’s placed on (top or bottom). This data links back to the schematic through component reference designators.

Routing Information

All copper traces are defined with their start and end points, width, and layer. The file also contains information about trace segments, arcs, and any curved routing.

Design Rules

EAGLE stores design rules within the .BRD file, including minimum trace width, clearance requirements, via sizes, and other manufacturing constraints.

How to Open a .BRD File

Opening a .BRD file depends on what you need to do with it—view, edit, or convert for manufacturing.

Opening .BRD Files in Autodesk EAGLE

The native method for opening Eagle .BRD files:

1. Launch Autodesk EAGLE
2. Go to File → Open → Board
3. Navigate to your .BRD file and select it
4. The board layout opens in the Layout Editor

If the associated .SCH file is in the same directory, EAGLE will prompt you to open both files together, maintaining the schematic-to-board linkage.

Opening .BRD Files in Other Software

Free Online .BRD Viewers

Several online tools let you view .BRD files without installing software:

Converting .BRD Files to Gerber Format

Most PCB manufacturers prefer Gerber files for production. Converting your Eagle .BRD file to Gerber format is essential before ordering boards.

Step-by-Step Gerber Export from EAGLE

1. Open your .BRD file in EAGLE
2. Run the drill configuration: File → Run ULP → drillcfg
3. Select “inch” as the output unit and click OK
4. Open the CAM Processor: File → CAM Processor
5. Load the Gerber job file: File → Open → Job
6. Select “gerb274x.cam” for 2-layer boards (or “gerb274x-4layer.cam” for 4-layer)
7. Click “Process Job” to generate Gerber files
8. Load “excellon.cam” and process again for drill files
9. Collect all output files into a ZIP archive

Gerber Files Generated from .BRD

A typical 2-layer board produces these files:

Direct .BRD Upload to Manufacturers

Some PCB fabricators accept Eagle .BRD files directly:

These manufacturers convert .BRD files internally using automated processes. While convenient, generating your own Gerbers gives you more control over the output and lets you verify the files before submission.

Importing .BRD Files into Other PCB Tools

If you need to migrate an Eagle design to another PCB tool, most major EDA packages support .BRD import.

Importing into Altium Designer

Altium provides a dedicated Eagle importer:

1. File → Import Wizard
2. Select “Import EAGLE Design Files and Libraries”
3. Choose your .BRD and .SCH files
4. Configure layer mapping if needed
5. Click Next to complete import
6. Review the generated .PcbDoc file

Altium supports EAGLE XML format files (version 6.4 and later). For older binary .BRD files, open them in EAGLE first and save in the newer format.

Importing into KiCad

KiCad can import Eagle designs through its built-in importer:

1. File → Import → Non-KiCad Project
2. Select “EAGLE schematic and board”
3. Choose your .BRD file
4. KiCad creates equivalent .kicad_pcb and .kicad_sch files

Note that some complex Eagle features may not translate perfectly to KiCad.

Read more PCB Files format:

What are .GBR and .PHO Files? Gerber File Extensions Guide

What are PCB Panelization Files? Complete Array Format Guide

What is .DSN File? Specctra Autorouter Format Explained

What is .kicad_pcb? KiCad PCB File Format Guide

What is .PcbDoc? Altium Designer PCB Format Explained

What is .PrjPcb? Altium Designer Project File Explained

What is .SchDoc? Altium Schematic File Explained

What is a .ASC File? PADS ASCII Format Explained

What is a .BRD File? Eagle PCB File Format Explained

What is a .DRC File? Design Rule Check Reports Explained

What is a .PCB File? Complete Protel/Altium PCB Format Guide

What is a .SES File? Complete Specctra Session File Guide for PCB Engineers

What is a BOM File? Bill of Materials Format for PCB Assembly

What is a CPL File? SMT Component Placement Guide

What is a Fabrication Drawing? PCB Fab Notes Explained

What is a Gerber Job File? Project Metadata Explained

What is a Netlist? PCB Connectivity Data Explained

What is a Pick and Place File? SMT Centroid Data Guide

What is a Stencil Gerber File? Complete Solder Paste Stencil Guide

What is an Aperture File? Gerber Tool Definition Guide

What is an Assembly Drawing? Complete PCB Assembly Documentation Guide

What is DXF in PCB Design? CAD Drawing Exchange Format Explained

What is Excellon? NC Drill File Format for PCB Manufacturing

What is GenCAD? Universal PCB Data Format Explained

What is Gerber RS-274X? The PCB Industry Standard Explained

What is Gerber X2? The Modern Gerber Format Guide

What is Gerber X3? Component Data in Gerber Files

What is HPGL? PCB Plotter File Format Guide

What is IGES? 3D PCB Model Format Explained

What is ODB++? Complete PCB Data Exchange Format Guide

What is PDF/A for PCB? Documentation Standards Guide

What is STEP File in PCB Design? 3D Model Exchange Guide

What is VRML in PCB? 3D Visualization Format Guide

Common .BRD File Issues and Solutions

Problem: Cannot Open Legacy .BRD File

Older .BRD files (pre-version 6) use binary format that newer tools can’t read directly.

Solution: Open the file in an older EAGLE version (available from Autodesk archives), then save it in XML format using “Save As.”

Problem: Schematic and Board Don’t Match

Forward/back annotation errors cause mismatches between .SCH and .BRD files.

Solution: In EAGLE, run the ERC (Electrical Rule Check) and use Tools → Errors to identify inconsistencies. Run “ratsnest” to update the air wires.

Problem: Import Fails in Altium/KiCad

The importer may reject corrupted or incompatible files.

Solution: Verify the .BRD file opens correctly in EAGLE first. Check that it’s XML format (version 6+). Try exporting from EAGLE to a fresh file.

Problem: Missing Layers After Import

Some layers may not map correctly during import to other tools.

Solution: Configure layer mapping manually during the import process. Document your original layer assignments for reference.

.BRD File vs. Other PCB File Formats

Understanding how .BRD compares to other formats helps you choose the right workflow:

The .BRD file is a design file, not a manufacturing file. It contains editable design data, while Gerber files are manufacturing outputs that describe the final board without design intelligence.

Useful Resources for Working with .BRD Files

Official Documentation

Free Software Downloads

Online Tools

Frequently Asked Questions

What software can open a .BRD file?

The primary software for opening Eagle .BRD files is Autodesk EAGLE, available for Windows, Mac, and Linux. Other options include Altium Designer (for import), Fusion 360 (which integrates EAGLE), KiCad (with import limitations), and EasyEDA (web-based). For viewing only, Altium 365 Viewer is a free online option that requires no installation.

Can I open a .BRD file without EAGLE?

Yes, but with limitations. For viewing, use free online tools like Altium 365 Viewer. For editing, you’ll need to import the file into another PCB design tool like KiCad or Altium Designer. Since EAGLE version 6+ uses XML format, you can also open the file in a text editor to view the raw design data, though this isn’t practical for design work.

How do I convert a .BRD file to Gerber for manufacturing?

Open the .BRD file in EAGLE, then use the CAM Processor (File → CAM Processor). Load the “gerb274x.cam” job file, click “Process Job” to generate Gerber files, then load “excellon.cam” and process again for drill files. Collect all generated files into a ZIP archive for your PCB manufacturer. Some manufacturers also accept .BRD files directly and convert them automatically.

What’s the difference between .BRD and .SCH files in EAGLE?

The .BRD file contains the physical PCB layout—component positions, copper traces, board outline, and manufacturing layers. The .SCH file contains the schematic diagram—symbols, electrical connections, and circuit logic. Both files are linked in an EAGLE project, and changes in one affect the other through forward and back-annotation. You need both files for a complete design, but only the .BRD file is used for PCB manufacturing.

Are all .BRD files compatible with each other?

No. While “.brd” is a common extension, different software uses incompatible formats. An Eagle .BRD file won’t open in Cadence Allegro, and an Allegro .BRD file won’t open in EAGLE. Even within EAGLE, older binary format files (pre-version 6) may not open in newer versions without conversion. Always verify which software created a .BRD file before attempting to open it, and use the appropriate tool for that specific format.

Best Practices for Managing .BRD Files

Working with .BRD files effectively requires good file management habits.

Version Control

Because modern Eagle .BRD files are XML-based text files, they work well with version control systems like Git. Tracking changes in your PCB designs helps you:

• Revert to previous versions if design changes cause problems
• Collaborate with team members without overwriting each other’s work
• Document the evolution of your design over time

File Naming Conventions

Adopt consistent naming for your design files:

• Include the project name and revision number: ProjectName_v1.2.brd
• Keep .BRD and .SCH files with matching names in the same directory
• Use underscores rather than spaces to avoid cross-platform issues

Backup Strategies

EAGLE creates automatic backup files with extensions like .b#1 through .b#9. Configure backup settings in Options → Backup to ensure you can recover from accidental changes or file corruption.

Working Effectively with .BRD Files

The .BRD file format has served the electronics industry well for decades. Whether you’re modifying an open-source design, collaborating with other engineers, or managing your own project archive, understanding how .BRD files work helps you navigate the PCB design workflow more effectively.

For new projects, EAGLE remains a solid choice due to its extensive library support, active community, and Fusion 360 integration. For opening legacy files or migrating designs, the XML-based format makes modern .BRD files accessible to a wide range of tools and workflows.

Remember that .BRD files are design files, not manufacturing files. Always generate proper Gerber outputs and verify them in a dedicated Gerber viewer before sending boards to fabrication. This extra step catches errors that could result in costly manufacturing mistakes.

The electronics design landscape continues to evolve, but the fundamental concepts behind .BRD files—defining physical layouts from electrical schematics—remain central to how we create the circuit boards that power our modern world.