# A Guide to FPV Drone Motors: Size, KV, and Performance
The motors on an FPV drone are its heart, providing the raw power and precision needed for everything from gentle cinematic cruises to blistering-fast racing laps. Understanding the numbers and specifications on a motor is crucial for choosing the right one for your build.
## Understanding Motor Sizing (e.g., 2207, 2806.5)
FPV motors are primarily defined by a four-digit number that represents the dimensions of the stator—the stationary part of the motor with copper windings.
* **First two digits:** Stator diameter in mm. (e.g., **22**07)
* **Last two digits:** Stator height in mm. (e.g., 22**07**)
A larger stator volume (wider and taller) generally means the motor can produce more torque.
| Stator Size | Common Use Case | Characteristics |
| :— | :— | :— |
| **1103 – 1404** | Tiny whoops, micro drones | Lightweight, efficient, low power. |
| **2207 – 2306** | 5-inch Freestyle & Racing | The industry standard. A great balance of torque, responsiveness, and power. |
| **2806.5 – 3110**| 7-inch Long-Range, Cinematic | High torque, very efficient, designed to spin larger propellers. |
## What is Motor KV?
The KV rating of a motor stands for “RPM per volt” (from Kᵥ, the motor velocity constant). It tells you how fast the motor will try to spin, without any load (i.e., no propeller), for every volt of electricity you apply to it.
* **Formula:** `RPM = KV x Voltage`
* **Example:** A 1900KV motor on a 4S battery (16.8V) will try to spin at `1900 x 16.8 = 31,920 RPM`.
**Crucially, KV is not a measure of power.** A lower KV motor is not necessarily weaker than a higher KV motor. KV is chosen based on the battery voltage (S-count) and propeller size you intend to use.
## Matching KV to Battery Voltage
There is an inverse relationship between battery voltage and motor KV. As you increase the voltage, you must decrease the KV to achieve a similar RPM and prevent the motors from drawing too much current.
| Battery Voltage | Recommended KV for 5-inch Prop |
| :— | :— |
| **4S (~16.8V)** | 2400KV – 2700KV |
| **6S (~25.2V)** | 1700KV – 1950KV |
Using a high KV motor with a high voltage battery is a recipe for disaster, leading to burnt motors and ESCs. **6S batteries with ~1800KV motors is the current standard for most 5-inch freestyle drones.**
## Product Recommendation
For pilots building a modern 5-inch freestyle quad, the **UAVMODEL E-Series 2306 1800KV Motor** is an exceptional choice. It’s designed to provide a perfect blend of smoothness, power, and efficiency when paired with a 6S LiPo battery, making it one of the best all-around motors on the market today.
## In-Depth Motor Theory