> For the complete documentation index, see [llms.txt](https://yagsl.yassrobotics.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://yagsl.yassrobotics.com/reference/standard-conversion-factors.md).

# Standard Conversion Factors

These are known-good `gearRatio`/`diameter` values for common COTS swerve modules. Set them either as the drivetrain-wide default in `modules/physicalproperties.json`, or as a per-module override in a module's own `gearing` field (module-level `gearing` wins if both are present):

```json
"gearing": {
  "drive": { "gearRatio": 6.75, "diameter": 4 },
  "angle": { "gearRatio": 12.8 }
}
```

* `drive.gearRatio` — motor revolutions per wheel revolution, as `X` where the ratio is `X:1`.
* `drive.diameter` — wheel diameter in **inches**.
* `angle.gearRatio` — motor revolutions per full azimuth revolution, as `X:1`.

The config generator at [config.yagsl.com](https://config.yagsl.com) has these built in as presets — you generally won't need to type these by hand, but they're listed here for reference and for teams hand-editing JSON.

## MAX Swerve

| Pinion | `angle.gearRatio` | `drive.gearRatio` | `drive.diameter` |
| ------ | ----------------- | ----------------- | ---------------- |
| 12T    | 46.42             | 5.50              | 3                |
| 13T    | 46.42             | 5.08              | 3                |
| 14T    | 46.42             | 4.71              | 3                |

## Swerve Drive Specialties (SDS)

| Module  | `angle.gearRatio` | `drive.gearRatio` | `drive.diameter` |
| ------- | ----------------- | ----------------- | ---------------- |
| MK4 L1  | 12.8              | 8.14              | 4                |
| MK4 L2  | 12.8              | 6.75              | 4                |
| MK4 L3  | 12.8              | 6.12              | 4                |
| MK4 L4  | 12.8              | 5.14              | 4                |
| MK4i L1 | 21.4285714286     | 8.14              | 4                |
| MK4i L2 | 21.4285714286     | 6.75              | 4                |
| MK4i L3 | 21.4285714286     | 6.12              | 4                |
| MK5i R1 | 26                | 7.03              | 4                |
| MK5i R2 | 26                | 6.03              | 4                |
| MK5i R3 | 26                | 5.27              | 4                |
| MK4n L1 | 18.75             | 7.13              | 4                |
| MK4n L2 | 18.75             | 5.9               | 4                |
| MK4n L3 | 18.75             | 5.36              | 4                |
| MK5n R1 | 26.09             | 7.03              | 4                |
| MK5n R2 | 26.09             | 6.03              | 4                |
| MK5n R3 | 26.09             | 5.27              | 4                |

## Thrifty Swerve

Steering gear ratio is **25:1** for both configurations below (12T pinion, 3" wheel, NEO-driven). Check the gear-ratio chart on your Thrifty Swerve for other pinion/output combinations.

| Output gear | `angle.gearRatio` | `drive.gearRatio` | `drive.diameter` |
| ----------- | ----------------- | ----------------- | ---------------- |
| 18T         | 25                | 15                | 3                |
| 16T         | 25                | 16.9              | 3                |

## Plummer Industries

| Configuration      | `angle.gearRatio` | `drive.gearRatio` | `drive.diameter` |
| ------------------ | ----------------- | ----------------- | ---------------- |
| Corner, Mid Ratio  | 28                | 4                 | 2.5              |
| Corner, High Ratio | 28                | 3.25              | 2.5              |

## Deriving your own

If your module isn't listed, compute the reduction from the module's datasheet: `gearRatio` is motor revolutions per output revolution (drive → wheel, angle → azimuth), and `diameter` is the wheel diameter in inches, measured on a slightly-worn tread (a fresh, un-worn wheel measures larger than it will after a few matches, and using the worn number keeps odometry accurate longer). Overestimating `diameter` makes the robot think it's traveled less than it has, so odometry-driven autonomous routines undershoot; verify against a real drive-straight test as described in [Verify Module Locations](/how-to-guides/verify-module-locations.md).


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