Gerber files are the de facto handoff format between PCB design and PCB manufacturing. If you have ever asked “what are Gerber files?”, “which Gerber files does my fab need?” or “Gerber vs ODB++ vs IPC-2581: which should I send?”, this Q&A-style guide answers those questions in plain engineering terms. What are Gerber files? A …
Gerber files are the de facto handoff format between PCB design and PCB manufacturing. If you have ever asked “what are Gerber files?”, “which Gerber files does my fab need?” or “Gerber vs ODB++ vs IPC-2581: which should I send?”, this Q&A-style guide answers those questions in plain engineering terms.
A Gerber file is a 2D vector image format (RS-274X, now maintained by Ucamco as the Gerber X2/X3 specification) that describes one layer of a printed circuit board: copper, solder mask, silkscreen, solder paste or board outline. Each layer of your design is exported as its own file, and the fabricator’s CAM software stacks them to rebuild the board.
Gerber files describe images, not intelligence. Classic RS-274X carries no netlist, no stackup and no component data. Gerber X2 adds attributes (layer function, file polarity, pad/via roles), and X3 adds component information for assembly, but most shops still receive plain RS-274X plus separate drill and assembly files.
A typical fabrication package for a 4-layer board contains:
For assembly you also send a BOM and pick-and-place (centroid/XY) file, and optionally an IPC-356 netlist so the fab can run electrical test against your intent.
Whatever the tool, always set units and format explicitly (e.g. mm, 4.6) and keep them consistent between Gerber and drill outputs.
Never ship Gerbers you have not viewed outside your CAD tool. Open them in an independent viewer (KiCad GerbView, the Ucamco Reference Gerber Viewer, or your fab’s online viewer) and check:
Most fabs also run their own DFM check and send an engineering query (EQ) if something is ambiguous: a clean package with a README minimises those delays.
| Format | What it carries | When to use |
|---|---|---|
| Gerber RS-274X | Layer images only; drill separate | Universal, accepted by every fab |
| Gerber X2 / X3 | Images + layer/pad attributes (+ components in X3) | Modern default if your fab supports it |
| ODB++ | Single database: layers, drill, netlist, stackup, components | Higher-mix or assembly-heavy builds; Siemens ecosystem |
| IPC-2581 | Open XML: full fab + assembly data in one file | Vendor-neutral “intelligent” handoff, growing support |
Gerber remains the safest universal choice. Intelligent formats reduce misinterpretation of stackup and netlist, so ask your fab what it prefers and, if in doubt, send Gerber X2 plus drill and ODB++ or IPC-2581.
AI-assisted design tools such as IntelCAD aim to catch many of these issues earlier (during layout and design review) so that the Gerber package you export reflects a board that already passes manufacturability checks. The Gerber, drill and fab-drawing package itself is still the contract with your manufacturer, so the review steps above still apply.
Gerber files tell a PCB manufacturer what each layer of the board looks like (copper, solder mask, silkscreen, paste and outline) so they can image, etch and finish the board exactly as designed.
Usually not. Holes are normally delivered in a separate Excellon NC drill file. Gerber X2 can describe drill data, but most fabs still expect Excellon drill files alongside the Gerbers.
Modern tools typically use .gbr for every layer, with the layer named in the filename. Older Protel-style extensions such as .GTL, .GBL, .GTS, .GTO and .GKO are still common and widely recognised.
Yes. Free viewers like KiCad GerbView, the Ucamco Reference Gerber Viewer, and most fabricators’ online viewers open Gerber and drill files without a full CAD license.
ODB++ carries more information (netlist, stackup, components) in one package, which reduces ambiguity. Gerber is more universally accepted. Neither is strictly better: use what your manufacturer supports, and Gerber X2 is a good modern default.
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