How to Convert Altium to KiCad — 2026 Migration Guide

KiCad 8 Has a Native Altium Importer

Unlike the reverse direction, KiCad 8 (released February 2024) reads Altium .PcbDoc and .SchDoc files directly via File > Import > Non-KiCad Project. The importer parses Altium's binary OLE2/CFB format, extracts copper geometry, nets, and components, and writes a clean KiCad project. Most boards convert in minutes; the post-import work is 3D model relinking and rule restatement, not the geometry conversion itself.

What the Importer Actually Reads

Altium files are Compound File Binary (CFB) containers — the same OLE2 storage format used by old Microsoft Office documents. KiCad 8's importer walks the CFB tree, parses each binary stream (Board, Components, Nets, Polygons, Tracks, Vias, Pads, Strings), and reconstructs the design in KiCad's native S-expression format. The work was open-sourced and integrated into KiCad's main branch in 2023, so the parser is auditable. The importer also handles .PcbLib (footprint libraries) and .SchLib (symbol libraries) for partial migrations.

What Transfers and What Needs Fix-Up

• Copper layers — clean transfer including blind/buried vias, polygons, thermal reliefs. Layer mapping is automatic for standard 2/4/6/8-layer stacks.
• Nets and components — placements, references, values, and net assignments transfer cleanly. Cross-probe between schematic and PCB works after import.
• 3D models — Altium STEP references don't auto-link. Either use KiCad's official 3D library (covers most common packages) or MakerSuite 3D's auto-inference which derives model URLs from footprint names.
• Design rules — track widths and clearances per net class transfer. Differential pair rules, length matching, and impedance constraints need restating in KiCad's syntax (half-day for high-speed boards).
• Custom pad shapes — Altium's complex pad shape library doesn't have 1:1 KiCad equivalents. Most exotic shapes degrade to closest standard; visually verify before fab.
• Schematic graphics — text frames, custom symbols, and decorative elements may render slightly differently. Functional content (nets, symbols, references) is faithful.

Five-Step Migration Workflow

1. Open pcbviewer.app — drop your .PcbDoc on MakerSuite 3D first to capture a baseline view of the original Altium board. This becomes your reference for verifying the conversion.
2. Open KiCad 8 > File > Import > Non-KiCad Project, point at the Altium project folder. Wait for the importer to walk all binary streams. A clean import takes 30 seconds to a few minutes depending on board complexity.
3. Open the imported .kicad_pcb in KiCad. Visual check: does the layer count match, do components show up where expected, are nets named consistently. Run DRC to find geometry issues the importer flagged.
4. Relink 3D models — for footprints with empty 3D references, use KiCad's official library or auto-inference. Check the 3D viewer (View > 3D Viewer) to confirm components render.
5. Verify by dropping the imported .kicad_pcb back on MakerSuite 3D and comparing tab-by-tab against the original .PcbDoc. Layer drift, missing zones, rotated parts, lost vias — all show up immediately in side-by-side 3D view.

Why This Migration Path Is Smoother

KiCad has strategic incentive to grow by accepting Altium projects, so the importer is actively maintained. The reverse path (KiCad → Altium) has no equivalent because Altium has commercial incentive against making it easy to leave. This asymmetry means: switching to KiCad is a one-afternoon job for most boards. Switching from KiCad to Altium is a multi-day rebuild. Plan accordingly when choosing your team's primary EDA.

When Altium to KiCad Conversions Happen

• License cost reduction — small team finds Altium subscription too expensive, KiCad delivers same capability for free
• Cross-platform workflow — Mac and Linux engineers can't run Altium natively, KiCad runs everywhere
• Open-source mandate — corporate or grant requirements specify open-source EDA tooling for delivered designs
• Hiring constraint — KiCad-trained engineers are easier to find than Altium-trained, especially for entry-level roles
• Long-term archival — KiCad's text-based S-expression format is human-readable, version-controllable, and won't bit-rot like binary CFB

Verify the Conversion in Your Browser

Both Altium and KiCad source files contain full design IP. Uploading them to cloud-based converters or viewers is a real risk for NDA work. MakerSuite 3D parses both formats entirely in your browser via JavaScript — no server, no upload, no cached copy. Drop the original .PcbDoc on one tab and the converted .kicad_pcb on another to compare layer by layer. Any silent regression shows up immediately in the 3D view, and your geometry never leaves the machine.