KV (RPM per Volt) refers to how many revolutions per minute (RPM) a brushless motor will spin per volt applied with no load. For example, a 2300KV motor spins at 23,000 RPM on a 10V supply. KV does not directly indicate power or torque, but helps determine how fast a motor spins. In FPV drones, KV is used to match motor behavior to battery voltage and propeller size for optimal performance.
What is KV of motor?
When a motor is given 1V (one volt) without any load (such as a propeller attached to the motor), the number of revolutions per minute (rpm) that the motor rotates is “KV”. For instance, without propellers installed, a 2300kv brushless motor running on a 3S LiPo battery (12.6V) will rotate at about 28,980 RPM (2300 x 12.6). Usually, the motor manufacturer specifies motor KV as a preliminary estimate.
Example:
- kV=RPM per 1 Volt
- k= The kV rating of the motor e.g, 2300
- V = Voltage input e.g. 12.6v
2300(kV rating) X 12.6(Voltage) = 28,980(Revolutions Per Minute)
| Motor KV | Battery Voltage (V) | No-load RPM (KV × V) |
|---|---|---|
| 1000 KV | 12.6V | 12,600 RPM |
| 2300 KV | 14.8V (4S) | 34,040 RPM |
| 1750 KV | 22.2V (6S) | 38,850 RPM |
| 2700 KV | 11.1V (3S) | 29,970 RPM |
How to choose kv of motor for different sizes of propellers?
When selecting a motor KV for your FPV drone, propeller size plays a critical role in determining performance and efficiency.
- Smaller and lighter props (like 3” or 4”) are typically paired with higher KV motors. These motors spin faster, delivering quick throttle response and greater thrust at the cost of higher current draw and increased heat.
- Larger props (such as 6” or 7”) are better matched with lower KV motors, which provide more torque at lower RPM. This helps maintain efficiency and reduce the strain on your motor and ESC.
Attempting to spin a large propeller with a high KV motor can lead to overheating, inefficient power usage, and even hardware damage. This is because higher KV motors need more current to generate the additional torque required to turn heavier props, resulting in excessive thermal buildup.
Rule of thumb:
- Use high KV motors with small props and lighter builds (e.g., racing quads)
- Use low KV motors with larger props and heavier builds (e.g., long-range or cinematic drones)
Further reading: Tutorial Propellers: Choose Best Suitable Propellers for Your FPV
How to choose motor KV for different batteries?
Here are the Recommended Motor KV Ranges for Common Battery Setups
| Battery Type | Prop Size | Recommended KV Range | Typical Use Case |
|---|---|---|---|
| 4S (14.8V) | 5 inch | 2300 – 2700 KV | Freestyle / Racing |
| 6S (22.2V) | 5 inch | 1600 – 1900 KV | Freestyle / Long-Range |
| 6S (22.2V) | 7 inch | 1100 – 1500 KV | Long-Range / Efficiency-Focused Builds |
| 4S (14.8V) | 3 inch | 3000 – 4000 KV | Toothpick / Micro Freestyle |
| 3S (11.1V) | 2.5 inch | 3500 – 5000 KV | Ultra-light Micros |
The ideal KV range for a brushless motor depends on your battery voltage and propeller size. Higher KV motors spin faster but require more current, while lower KV motors offer better torque and efficiency for longer flights.
What is the best motor KV for 4S 5-inch FPV?
For your 5-inch freestyle, if you decide to go with 4S, pick a motor KV in the range of approximately 2300 to 2700.
| Battery | Motor KV | Prop Size | Use Case |
|---|---|---|---|
| 4S | 2300–2700 KV | 5 inch | Freestyle / Racing |
| 6S | 1600–1900 KV | 5 inch | Long-range / Cinematic |
What is the best motor KV for 6S 5-inch FPV?
Select a 5-inch FPV drone motor with a voltage range of 1600 kV to 1800 kV if you decide to use 6S. Take MEPS 2207, for example.
For the 6s FPV, if you want to fly more distance, the 1750kv motor is the best motor, because when the throttle reaches 100%, the current is 36.5A, which is lower than 46A. This may cause lower heat generation and more farther away.
For the 6s FPV, if you want to keep your FPV drone carrying more things, the 1950kv is the best motor kv, because when the throttle reaches 100%, the thrust is 1769.8g, which is higher than 1641.2g.
Motor KV vs. Torque Constant
Although motor KV has an effect on the torque constant, it does not directly alter torque. The amount of current needed to generate a specific amount of torque is determined by a motor’s torque constant. The real torque produced is unaffected by motor KV; coil resistance, air gap, and magnet strength all have a far greater impact on torque generation.
In comparison to lower KV motors, higher KV motors require more current to produce the same amount of torque due to their greater torque constant. The higher KV motor needs more current to produce the same amount of torque, which causes extra losses in the battery, ESC, and cables. Furthermore, less magnetic flux is produced, and the motor becomes hotter as a result of the increased current. In general, if you were to fly at the same speed as the lower KV engine, the higher KV motor would be less efficient.
As a result, it’s wise to strive to keep KV reasonable rather than excessive. This is particularly crucial when constructing a long-range rig when efficiency and flight time are given first priority.
| KV Rating | Thrust | Efficiency | Torque | Heat Generation | Application |
|---|---|---|---|---|---|
| Low KV (1000–1600) | Medium | High | High | Low | Long-range / Cinewhoop |
| Mid KV (1700–2300) | Balanced | Balanced | Balanced | Medium | Freestyle / General FPV |
| High KV (2400–2700+) | High | Low | Low | High | Racing / Lightweight Builds |
Is higher KV better?
It is evident that greater Kv does not necessarily equate to better. All that is shown is the motor’s RPM in relation to a 1V voltage constant. Increased voltage results in increased current as well as higher RPM.
If the current is too high, your motor will overheat. In the gollowing chart, it reveals the relationship between motor kv and pro size, cell, motor size and lipo battery in detail.
| Pro | Style | Cell | brushless motor sizes Motor Size | Motor kv | LiPo Battery (mAh) |
| 31mm Whoop | 1S | 0603, 0802 | 18000-25000 | 300-450 | |
| 2S | 0802 | 12000 | 300 | ||
| 40mm Whoop | 1S | 0802, 1102 | 15000-18000 | 450 | |
| 2S | 0802, 0806, 1103 | 10000-16000 | 300-450 | ||
| 3S | 1102, 1103 | 8000-11000 | 300-450 | ||
| 2″ Triblade | 2S | 1103, 1105, 1106 | 6000-11000 | 300-450 | |
| 3S | 1104, 1105, 1106 | 5500-7500 | 300-450 | ||
| 4S | 1105, 1106 | 5000-6000 | 450-650 | ||
| 2.5″ Triblade | 2S | 1104 | 5000-6000 | 300 | |
| 3S | 1106 | 4500 | 650 | ||
| 4S | 1304, 1404 | 4500-5000 | 450-850 | ||
| 2.5″ Two-Blade (65mm) | Ultralight | 1S | 1102 | 13500 | 300 |
| Ultralight | 2S | 1103, 1104 | 7000-10000 | 450-520 | |
| Ultralight | 3S | 1104, 1105, 1106, 1203, 1204 | 6000-8000 | 300-650 | |
| Ultralight | 4S | 1104, 1105, 1106, 1203, 1204 | 4000-4500 | 450 | |
| 3″ Triblade | Freestyle | 2S | 1404 | 4500-5000 | |
| Freestyle | 3S | 1407, 1408, 1507 | 3500-4500 | 550-850 | |
| Freestyle | 4S | 1306, 1407, 1408, 1507, 1606 | 3000-4200 | 450-1000 | |
| Freestyle | 6S | 1408, 1507, 1606 | 2800-3000 | 550-650 | |
| 3″ Two-Blade | Long Range | 1S | 1103, 1202 | 11000 | Li-Ion 2500-3000mAh |
| Ultralight | 1S | 1103, 1202, 1202.5 | 11000-14000 | 450 | |
| Ultralight | 2S | 1105, 1106, 1203, 1204, 1303 | 6000-8000 | 450 | |
| Ultralight | 3S | 1105, 1106, 1108, 1203, 1204, 1207, 1303, 1304, 1404 | 4500-6500 | 300-450 | |
| Ultralight | 4S | 1105, 1106, 1108, 1203, 1204, 1207, 1303, 1304, 1404 | 3500-5000 | 450-550 | |
| 3″ Cinewhoop | 4S | 1404, 1408, 1507, 2203, 2204 | 3800-4600 | 850-1300 | |
| 6S | 1507, 2203, 2204 | 2800 | 850 | ||
| 4″ Triblade | Freestyle | 3S | |||
| Freestyle | 4S | 1407, 1507, 1606 | 3000-4000 | 850-1000 | |
| Freestyle | 6S | 1606 | 2000-3000 | 600-850 | |
| 4″ Two-Blade | Ultralight | 3S | 1306, 1404, 1406, 1408, 1504, 1505 | 3500-4500 | 650-850 |
| Ultralight | 4S | 1306, 1404, 1406, 1408, 1504, 1505 | 2500-3000 | 450-650 | |
| Long Range | 3S | 1404 | 3500-4000 | Li-Ion 2500-3000mAh | |
| Long Range | 4S | 1404 | 2500-3000 | Li-Ion 2500-3000mAh | |
| 5″ Triblade | Freestyle | 4S | 2306, 2207, 2306.5, 2207.5 | 2300 – 2700 | 1300-1500 |
| Freestyle | 6S | 2207, 2207.5, 2208, 2308 | 1700 – 1950 | 1000-1300 | |
| 5″ Two-Blade | Ultralight | 4S | 1606, 1806, 2004, 2204, 2205 | 2300-3000 | 750-1000 |
| Ultralight | 6S | 1606, 1806, 2004, 2204, 2205 | 1600-2300 | 450-700 | |
| 6″ | Freestyle | 4S | 2207, 2207.5, 2208, 2405, 2407, 2408 | 2100 – 2500 | 1300-1800 |
| Freestyle | 6S | 2207, 2207.5, 2208, 2405, 2407, 2408 | 1500-1800 | 1000-1500 | |
| 7″ | Freestyle | 6S | 2510, 2806, 2806.5, 2808, 3106.5 | 980-1450 | 2200 |
| Long Range | 4S | 2408, 2507, 2508, 2806, 2806.5 | 1700-1900 | Li-ion 2500-3000mAh | |
| Long Range | 6S | 2408, 2507, 2508, 2806, 2806.5 | 980-1450 | Li-ion 2500-3000mAh |
FAQ
Q1: Is higher KV better for drone racing?
Not always. Higher KV motors spin faster but often produce less torque, which means they’re suitable for lighter props and smaller drones, especially when using 4S batteries. However, extremely high KV can cause inefficiencies, overheating, or reduced control. For racing, most pilots prefer motors in the 2400–2700KV range (for 5-inch 4S builds), balancing thrust and responsiveness without sacrificing efficiency or stability.
Q2: How do I choose the right KV for my FPV build?
To choose the right KV, consider your battery voltage, propeller size, and flying style:
- Freestyle on 6S: 1700–1900KV
- Freestyle on 4S: 2300–2500KV
- Racing on 4S: 2500–2700KV
- Long-range (efficiency-focused): 1500–1800KV
- Cinewhoop / heavy lift: Lower KV (1200–1600KV) with large props and high torque
Also, consider the motor’s stator size and build quality to ensure consistent performance. Matching KV correctly ensures balanced thrust, efficiency, and flight control.
Q3: What does a 1000 KV motor mean?
A 1000 KV motor will theoretically spin at 1000 revolutions per minute (RPM) for every volt of electricity supplied with no load. For example, on a 10V battery, it will spin at 10,000 RPM (1000 × 10). Lower KV motors like 1000 KV are typically used in applications where torque and efficiency are prioritized over raw speed—such as in long-range or heavy-lift drone setups.
Q4: Is a higher KV motor faster?
Yes, in general, higher KV motors spin faster because they produce more RPM per volt. However, higher KV doesn’t always mean better performance. It usually results in less torque and greater power consumption. While higher KV motors are common in lightweight, high-speed racing drones, they may cause overheating or reduced efficiency in heavier builds or when paired with large propellers