# Motor KV and prop/voltage matching

> What KV motor for 4S or 6S on a 5 inch drone?

- Category: Drone design › Drone frame layouts
- Kind: Standard part
- Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
- Page: https://xemstudio.com/objects/motor-kv-matching/ · JSON: https://xemstudio.com/api/geometry?object=motor-kv-matching · Plain text: https://xemstudio.com/objects/motor-kv-matching/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files Xem Studio Design License (free to use and sell from, not to redistribute as files: https://xemstudio.com/license/)
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- KV is rpm per volt unloaded; 2300 KV on 16.8 V gives 38,640 rpm (GetFPV). Higher voltage needs lower KV and bigger props need lower KV (Unmanned Tech Shop).
- Oscar Liang's table: 5 in freestyle 2300-2700 KV on 4S, 1700-2100 KV on 6S; 7 in 1200-1400 KV on 6S. Low-KV motors on fewer cells with big props are most efficient (ArduPilot).
- The file is a reference example built by Xem Studio from the numbers above (5x4.3 tri-blade named in Unmanned Tech Shop guide.). Sizes the sources do not fix are illustrative; scale the example to your own vehicle.

## Sizes

| parameter | value or range | source |
|---|---|---|
| 5 in freestyle 4S | 2300-2700 KV | Oscar Liang table |
| 5 in freestyle 6S | 1700-2100 KV | Oscar Liang table |
| 5 in racing 6S | 1900-2300 KV | Oscar Liang table |
| 7 in 6S | 1200-1400 KV | Oscar Liang table |
| 3 in 4S | 3000-4200 KV | Oscar Liang table |
| Battery rule | about half dry weight | Oscar Liang |
| Hover throttle target | ~50% | ArduPilot |

## Where the files are

- GetFPV: [What is a drone motor?](https://www.getfpv.com/motors/what-is-a-drone-motor.html) — web — Publisher's page; dimensions are facts
- Oscar Liang: [Prop, motor, LiPo and weight table](https://oscarliang.com/table-prop-motor-lipo-weight/) — web — Publisher's page; dimensions are facts
- Unmanned Tech Shop: [Motor selection guide for FPV drones by class and frame size](https://www.unmannedtechshop.co.uk/de/blogs/knowledge-base/motor-selection-guide-fpv-drones-by-class-frame-size) — web — Publisher's page; dimensions are facts
- ArduPilot: [Archived: Advanced MultiCopter Design](https://ardupilot.org/copter/docs/advanced-multicopter-design.html) — web — Publisher's page; dimensions are facts
- Unmanned Tech Shop: [FPV drone propeller size guide: how to choose props](https://www.unmannedtechshop.co.uk/de/blogs/knowledge-base/fpv-drone-propeller-size-guide-how-to-choose) — web — Publisher's page; dimensions are facts

## Free STEP/STL (1 parts, Xem Studio Design License, Xem Studio)

Index: https://xemstudio.com/files/hardware/motor-kv-matching/index.json · license: https://xemstudio.com/files/hardware/motor-kv-matching/LICENSE.md

- motor-kv-matching-propeller: [STEP](https://xemstudio.com/files/hardware/motor-kv-matching/motor-kv-matching-propeller.step) · [STL](https://xemstudio.com/files/hardware/motor-kv-matching/motor-kv-matching-propeller.stl) — 5×4.3 in propeller, 3 blades: each section set at the geometric pitch angle atan(P / 2πr); chord and section illustrative

## Questions

**Why lower KV on 6S?**

Higher voltage raises rpm, so KV comes down (Unmanned Tech Shop).

## Fits with

- [True X quad frame](https://xemstudio.com/objects/true-x-frame/)
- [Stretched X frame](https://xemstudio.com/objects/stretched-x-frame/)
- [Squashed (wide) X frame](https://xemstudio.com/objects/squashed-x-frame/)
- [Hybrid X frame](https://xemstudio.com/objects/hybrid-x-frame/)
- [Deadcat frame](https://xemstudio.com/objects/deadcat-frame/)
- [H frame](https://xemstudio.com/objects/h-frame/)