Mounting patterns
Stack and motor mounting patterns are measured in millimetres between screw holes. The numbers are simple; the names given to them in shops are not, and two of the commonest names are rounded off by half a millimetre.
What the number measures
A mounting pattern is the distance between the centres of the mounting holes, given as width by depth in millimetres. A 20×20 flight controller has four holes in a 20 mm square. A frame's standoffs are drilled to one or more of these patterns, and a board fits if the frame accepts a pattern the board has.
A frame commonly accepts more than one, and boards are sometimes drilled for two, which is why Buildlas records both sides as sets and passes the check when anything is shared, rather than demanding that two single values match.
- Flight controller mount adapter, 30.5 / 25.5 / 20 / 16 mmSpeedyFPV · Manufacturer · read 2026-07-27
Stack patterns
Flight controllers, ESCs, AIO boards and some video transmitters.
| Pattern | Also sold as | Typical use |
|---|---|---|
| 16×16 mm | – | Small and micro builds |
| 20×20 mm | M2 20×20 | The most common pattern, 3 inch and up |
| 25.5×25.5 mm | "25×25" | Larger micro and mid-size boards |
| 30.5×30.5 mm | "30×30" | Full-size 5 inch and larger |
- Flight controller mount adapter, 30.5 / 25.5 / 20 / 16 mmSpeedyFPV · Manufacturer · read 2026-07-27
Motor patterns
The bolt circle on the bottom of the motor, against the frame arm.
| Pattern | Screws | Typical class |
|---|---|---|
| 9×9 mm | M2 | Small whoop, 1–2 inch |
| 12×12 mm | M2 | 3 inch and similar |
| 16×16 mm | M3 | 5 inch class |
| 16×19 mm | M3 | 5 inch class |
- How to Choose FPV Drone MotorsOscar Liang · Editorial · read 2026-07-27
Adapters exist
Adapter plates are sold that convert between the common stack patterns, so a mismatch is not always the end of the build. What an adapter costs you is stack height, which is the thing in shortest supply in a small frame.
- Flight controller mount adapter, 30.5 / 25.5 / 20 / 16 mmSpeedyFPV · Manufacturer · read 2026-07-27
See this against real products
The planner reads these same properties off every product in the catalog and tells you what each pairing does with your build.