Listed gear-ratio data for 2021 Mariner 20 HP outboards. Match your exact model and lower unit; some models may have more than one gearcase configuration.
2021 Mariner 20 HP
Listed ratio values: 2.15:1
| Model | Gear ratio |
|---|---|
| F20 EFI FourStroke | 2.15:1 |
Use the ratio that matches your exact outboard model and lower unit, then enter it in the PropSlip calculator.