Setup Grid and Avoid My Mistakes

Before reading further, you can watch the companion video where I demonstrate how incorrect grid settings can cause serious connection errors in KiCad and how to fix them efficiently.

Introduction

When creating schematics in KiCad, using the correct grid settings is crucial to ensure that electrical connections between components are accurate.
If your wires or symbol pins do not align perfectly on the grid, KiCad may interpret them as unconnected—even if they visually appear connected. This can result in hundreds of warnings during the Electrical Rules Check (ERC) and cause connectivity issues later during PCB layout.

In this guide, we will review how to set up the correct schematic grid, understand why this is essential, and learn how to avoid the mistakes that can waste valuable design time.

The Problem with Incorrect Grid Settings

When designing the LattePanda Mu Carrier schematic, I initially used a grid size of 0.25 mm, which is just under 10 mils.
Although the schematic appeared visually correct and all components seemed to snap into place, the ERC revealed hundreds of warnings indicating “Symbol pin or wire end off connection grid.”

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This meant that many wire endpoints were slightly misaligned, leaving connections incomplete. As a result, the electrical continuity was broken, and the design could not be trusted.
Fixing this required switching to a larger grid size and manually repairing all the broken connections—an error that could have been avoided with correct setup from the start.

Recommended Grid Configuration

Before you begin drawing your schematic, open KiCad → Preferences → Schematic Editor → Grid and configure the grid as follows:

You can switch between grids quickly using Option + 1 and Option + 2 on macOS, or the equivalent shortcuts on your system.
These two grid sizes are sufficient for nearly all schematic work, as most symbols in KiCad’s official libraries are designed around 25–50 mil grid intervals.

Why Grid Alignment Matters

Grid alignment directly affects connectivity and electrical integrity.
When both a wire endpoint and a pin center are placed exactly on a grid intersection, KiCad registers them as connected.
If one is even slightly off the grid, the ERC cannot verify the connection, resulting in “unconnected” warnings—even though the line visually touches the pin.

A correct grid ensures that:

• Each wire and pin connection snaps precisely to the same coordinate.
• The schematic is logically consistent and error-free.
• The PCB layout process proceeds without missing nets or floating connections.

Using a grid that matches symbol pin spacing (25 or 50 mils) guarantees that components from both KiCad’s standard library and custom symbol sets will connect reliably.

Visual Example of Grid Scaling

Here is what each grid size looks like when zoomed in the schematic editor:

By starting with these standard grids, you can avoid connection errors, maintain consistent alignment, and ensure your schematic remains clean and easy to read.

Checking for Connection Errors

After adjusting your grid, always run an Electrical Rules Check (ERC) from the schematic editor’s toolbar.
If the grid is set correctly, you should see zero warnings for “off-grid connections.” Remaining errors may simply indicate unconnected symbols or unfinished sections, which is normal during early design stages.

Conclusion

Using the correct schematic grid in KiCad is a simple but critical step that ensures accurate electrical connections and clean project organization.
Before you start wiring the schematic for your LattePanda Mu Carrier project, verify that your grid settings are correct—25 mils and 50 mils are the optimal values for this design.

By establishing these grids early, you will prevent hundreds of avoidable warnings, avoid frustrating debugging sessions, and maintain a professional-quality schematic that transitions seamlessly into PCB layout.

Ready for the next tutorial in this series? Here's the next one, or choose an alternative from the list of articles in the side bar. There's also lots of interesting article in our Blog. where you can read about off-grid communication technologies, electronics test equipment, course updates, and much more.