You've undoubtedly heard of "KV rating" if you've ever gone shopping for brushless motors for your robot, drone, RC car, or any other electric-powered project. When choosing a motor, it's one of the most crucial specifications to take into account, but what does it really mean?
To help you choose the best KV for your next build, let's simplify the process.
What is KV Rating?
What is KV Rating?
RPM per Volt (RPM/V) is represented by the symbol KV. Without a load, it indicates how many revolutions per minute (RPM) the motor will spin for every volt of applied electricity.
For instance, when there is no load (no propeller, gear, or wheel attached), a 1000KV motor running on a 12V battery should theoretically spin at 12,000 RPM (1000 x 12).
High KV vs Low KV: What’s the Difference?
| KV Rating | RPM (Speed) | Torque | Best Used For |
| High KV | High RPM | Low Torque | Racing drones, RC cars, high-speed setups |
| Low KV | Low RPM | High torque | Drones with large props, robots, e-bikes |
High KV Motors
- At the same voltage, high KV motors spin more quickly.
- Better for builds that are lightweight or focused on speed
- Usually used with wheels or smaller props
Low KV Motors
- Have more torque but spin more slowly.
- Perfect for situations requiring a lot of pulling power or for heavier loads
- Perform well with bigger wheels or props.
How to Choose the Right KV Rating
How to Choose the Right KV Rating
The following are some broad rules:
- For Racing Drones use motors ranging from 2300KV to 2700KV on a 4S battery. Choose 1600KV to 1900KV for 6S.
- For long-range or cinematic drones use low KV motors (900–1500KV) with large propellers and higher voltage (6S+).
- For DIY EVs or combat robots, search for low KV motors (100–1000KV) that offer more torque to move heavy wheels or parts.
- For RC cars high KV motors (3000KV+) are used, while low KV motors (1000–2000KV) are used for torque and improved control.
Final Thoughts
When it comes to matching your motor to your power system and the goal of your project, the KV rating is crucial. Depending on what you're building, it all comes down to striking the correct balance between torque and speed.
Pro Tip: When selecting a motor, always take into account the motor's size, voltage, load, and compatibility with ESC in addition to KV. Better performance, longer runtime, and fewer failures are the results of a well-matched system.
Need Help Choosing the Right Motor?
We have a wide selection of brushless motors with comprehensive specifications in stock at Technobotix, making it simple to find the ideal one for your project.
