The Ultimate RC Motor Sizes Chart Guide: From Brushed to Brushless Systems

Understanding RC motor sizes isn’t just about numbers—it’s about matching power to purpose. Whether you’re building a crawler, a racer, or a drone, motor dimensions, KV ratings, and power specifications dictate performance. Brushed systems rely on legacy codes (e.g., 380, 540) for physical dimensions, while brushless motors (e.g., 3650) define their power core via stator measurements. Aircraft prioritize thrust-to-weight ratios, cars demand torque curves, and drones optimize thrust efficiency. This guide decodes sizing standards across platforms and provides actionable charts to simplify motor selection.

How RC Motor Sizes Are Classified and Measured

RC motors use standardized size codes (e.g., 380, 540, 3652) that indicate physical dimensions and performance tiers. Two primary systems exist:

• Brushed Motors: Follow legacy codes like 380 or 540, derived from early industrial motors. The number correlates with case length and diameter. For example, a 540 motor typically measures ≈35mm in diameter and 50mm long.
• Brushless Motors: Use a modern format (e.g., 3652). Here, “36” denotes a 36mm stator diameter, and “52” indicates a 52mm stator length. This directly reflects the power-generating core size.

For aircraft, motor selection revolves around prop compatibility and lift dynamics. Cars require torque-optimized sizing for terrain dominance, while drones demand thrust-scaled stators for agile flight. Misapplication risks heat buildup or power starvation—cross-reference these charts meticulously.

To identify a motor’s size:

1. Check labels or spec sheets for size codes.
2. Physically measure the stator (brushless) or can (brushed).
3. Cross-reference with manufacturer charts for torque/rpm ranges.
   

Real-World Tip: A mismatch between motor size and application (e.g., oversized drone motors) causes inefficiency, heat, or premature failure. For an expanded guide, see RC Car Electric Motors Explained.

Case Study: The 380-Size Brushed Motor

The 380 motor (often labeled 2838) is a compact powerhouse common in 1/18-scale vehicles. Key specs:

• Dimensions: ≈28mm diameter × 38mm length
• Voltage Range: 3-9V (2-3S LiPo)
• Typical RPM: 15,000–25,000 (under load)
• Weight: ≈80g

Used in lightweight buggies and crawlers, it balances speed and torque without overwhelming small drivetrains. Compare to its sibling:

The 540 Motor: Larger (35mm × 50mm), heavier (156g3), and suited for 1/10-scale applications. Generates higher torque but draws more current (7.92A at 7.2V vs. ≈4A for a 380).

RC Brushless Motor Size Chart (Spektrum Example)

In car racing, brushless sizing directly impacts acceleration and thermal management. Spektrum’s 3660 motor (36×60mm stator) delivers 1900-3300KV and 800W—tailored for 1/10 short-course trucks battling high-traction surfaces. Its 52mm stator length extends torque curves, allowing aggressive gearing without overheating. Conversely, their compact 1000-size (25×12mm) powers 1/18 drift cars with 5000KV bursts for rapid direction changes. Larger 4268 motors (42×68mm) handle heavy 1/8 buggies with 2400W output.

Here’s a condensed chart:

Note: Spektrum’s “Smart” motors integrate sensors for smoother low-speed control—critical in crawlers.

Brushed Motor Size Chart

Brushed motors excel in low-speed control scenarios. The 380-size (28×38mm) drives 1/18 trail trucks like Traxxas TRX-4M, where its 20,000 RPM and 4A draw provide hours of scale crawling without cogging. Larger 550 motors (36×66mm) handle 1/8 rock racers, leveraging brute-force 85A tolerance to conquer vertical obstacles—proving brushed tech’s enduring value in high-torque, low-cost builds.

Critical Spec: Brushed motors list “Turns” (e.g., 20T). Lower turns = higher rpm/less torque. A 20T crawler motor (like RC4WD’s) prioritizes torque over top speed.

Aircraft Brushless Motor Size Chart

For planes, thrust-to-weight ratio and KV dictate motor choice. Match prop size and battery voltage using this framework:

High-KV motors (e.g., 1400KV) pair with small props for speedsters. Low-KV (e.g., 190KV) suits large multirotors with big props.

Car Brushless Motor Size Chart

Vehicle weight and terrain determine optimal motor size:

Note: High-KV (e.g., 3300KV) motors in 1/10 crawlers cause cogging—sensored ESCs mitigate this.

Drone Brushless Motor Size Chart

Drone motors prioritize thrust efficiency like the 2207 (22mm bell × 7mm height) balance power and efficiency. On a 5″ freestyle quad, a 2500KV variant spinning 5040 props generates 1,500g thrust per motor—enabling explosive maneuvers at 6S voltage. Smaller 1106 motors (11×6mm) propel micro drones under 100g, where ultra-high KV (6500) compensates for tiny prop wash.
Key specs:

For quadcopters, thrust should be ≥2× the craft’s weight. Use our Quadcopter Power Calculator to optimize.

Motor and ESC Compatibility Chart

Mismatched electronics cause catastrophic failure.

Key rules:

• ESC current rating must exceed motor peak draw by 20%.
• Voltage range should align (e.g., 6S drone motors need 6S ESCs).
• Sensored ESCs (e.g., Hobbywing Xerun) eliminate cogging in low-RPM crawlers.

Golden Rule: ESC current rating should exceed the motor’s max draw by 20%. For example, a 45A peak motor (like the EV Craft 3536) needs a ≥50A ESC.

By mastering these charts—and pairing motors with ESCs that exceed current needs by 20%—you transform raw specs into unbreakable speed, control, and reliability on any terrain or sky.

Selecting the right RC motor size transcends mere dimensions—it demands synergy between KV ratings, ESC compatibility, and application physics. Brushed motors like the 380 deliver cost-effective precision in small-scale vehicles, while brushless systems (e.g., Spektrum’s 3660) unleash efficiency in demanding environments. For drones, thrust-to-weight ratios dictate stator size choices, and across all platforms, ESC pairings safeguard against thermal failure. By leveraging these charts and principles, you transform technical specifications into tangible speed, torque, and reliability—whether carving racetracks or conquering backcountry trails.