Guide to RC Servo Size Chart: Standard, Micro, and High-Torque Charts
Selecting the right RC servo size isn’t just about fitting components—it’s about unlocking peak performance in every turn, climb, or maneuver. Whether you’re tuning a competition buggy, building a scale crawler, or dialing in a high-speed aircraft, precise dimensional matching ensures optimal torque delivery, weight distribution, and control responsiveness. This expanded guide integrates deep technical insights with real-world application charts to help you navigate RC servo sizing like a pro.
Demystifying RC Servo Size Classification
RC servos follow three-tier size standards based on length, mounting patterns, and motor-gearbox integration:
| Category | Dimensions (L×W×H) | Weight | Primary Use Cases |
|---|---|---|---|
| Standard | ≈40.5×20×38.5mm | 40-65g | 1/8–1/10 cars, 1.5m+ wingspan aircraft |
| Mini | ≈30×15×29mm | 20-30g | 1/12 cars, 800-1200mm drones |
| Micro | ≤23×12×24mm | 3-12g | 1/18 crawlers, park flyers |
Aircraft-Specific Sizing Examples:
- Micro (9g): Elevator/rudder control in foamies (e.g., E-flite Timber X: 23×12×27.3mm)
- Standard (40mm class): Ailerons in 2m gas planes (e.g., Hitec HS-645MG: 40×20×38mm)
- High-Voltage (60mm+): Jet turbines/3D aerobatics (e.g., MKS HBL880: 65.5×30.2×58.3mm)
Major RC Servo Types by Technology
- Brushed vs. Brushless Motors:
- Brushed: Lower cost (e.g., MG996R), use carbon brushes, limited lifespan
- Brushless: Higher efficiency/speed (e.g., DS-B008-C), ideal for competition rigs
- Gear Materials:
- Nylon: Lightweight/quiet (Blue Bird BMS-410) but prone to strip under shock
- Metal: Durable under load (e.g., MG996R full steel gears)
- Hybrid: Nylon-core with metal critical gears.
- Control Type:
- Analog: Lower refresh rates (e.g., MG996R: 333Hz)
- Digital: Faster response/adjustable deadband (e.g., OMG ST-20DM)
Standard Servo Sizes Chart for Cars, Crawlers & Boats
Standard-sized servos (≈40×20×40mm) dominate ground vehicles. This chart compares critical specs across disciplines:
| Application | Dimensions (L×W×H, mm) | Weight | Torque | Voltage | Example Model |
|---|---|---|---|---|---|
| 1/10 Touring Car | 40.5×20×38.5 | 42g | 4.4kg-cm | 6.0V | Blue Bird BMS-410 |
| 1/10 Competition Buggy | 41×20×40 | 64g | 20kg-cm | 7.4-8.4V | OMG ST-20DM |
| 1/8 Monster Truck | 40.7×19.7×42.9 | 55g | 11kg-cm | 6.0V | MG996R |
| 1/5 Scale Desert Truck | 40×20×42 | 74g | 25kg-cm (8.4V) | 8.4V | OMG ST-25DF |
| Large-Scale Crawler | 95.5×60.5×102.6 | 530g | 380kg-cm (24V) | 24V | Zanrobot 380kg |
| Deep-Water Crawler | 41×20×40 | 64g | 20kg-cm | 7.4V | OMG ST-20DM (IP66) |
| Competition Boat | 40×20×42 | 74g | 23kg-cm (7.4V) | 8.4V | OMG ST-25DF |
| Rock Crawler | 40.7×19.7×42.9 | 55g | 11kg-cm | 6.0V | Savox SC-0251MG |
Design Notes:
- Low-profile (≤38.5mm height) servos prevent chassis scraping in slammed drift cars.
- Narrow-width (≤19.7mm) units clear axle components in crawlers like TRX-4.
- HV-compatible (≥7.4V) models harness LiPo power without external BECs.
Micro & Sub-Micro RC Servo Size Chart
For compact builds, micro-servos (≤24mm length) balance weight savings and control authority:
| Application | Dimensions (mm) | Weight | Torque (4.8V) | Speed | Model Example |
|---|---|---|---|---|---|
| 1/18 Scale Crawler | 23.6×11.4×21.1 | 10.8g | 2.5kg-cm | 0.12s/60° | Sanwa 94809 |
| 250mm Quadcopter | 22.6×9.9×23.6 | 9.5g | 3.1kg-cm | 0.12s/60° | MKS DS450 |
| Park Flyer Aileron | 22.1×10.9×23.1 | 9.1g | 1.6kg-cm | 0.10s/60° | Thunder Tiger C1016 |
| Indoor Helicopter | 12×6×22 | 2.9g | 0.3kg-cm | 0.15s/60° | JX SSV-9766MG |
| Robotic Arm Joint | 23×12×27.3 | 9g | 1.5kg-cm | 0.13s/60° | SG90 |
| FPV Camera Gimbal | 20.5×9.8×22.5 | 7.2g | 1.8kg-cm | 0.09s/60° | Power HD Micro |
Selection Guidelines:
- Sub-10g servos prevent tail-heavy drones from losing COG balance.
- Metal-gear versions (Futaba S3156MG) survive crash impacts in micro crawlers.
- <0.10s speed is critical for FPV gimbal stabilization.
Large and High-Torque RC Servo Performance Chart
When brute force dominates finesse, these servos deliver unstoppable power:
| Model | Dimensions (mm) | Torque Peak | Voltage | Gear Material | Best For |
|---|---|---|---|---|---|
| JX CLS-6321HV | 40×20×44.5 | 42kg-cm | 8.4V | Titanium | Competition crawlers |
| ProModeler DS630BLHV | 65.5×30.2×58.3 | 58kg-cm | 8.4V | Hardened steel | 1/5 scale desert runs |
| MKS HBL880 | 47.2×25.8×44.5 | 55kg-cm | 8.4V | Titanium hybrid | Jet turbine vectoring |
| AGFRC A86BHM | 41.5×21×40.5 | 45kg-cm | 8.4V | CNC aluminum | Rock bouncers |
| HiTec D845WP | 40×20×40 | 35kg-cm | 7.4V | Stainless steel | Saltwater boats |
| Savox SB-2290SG | 40.3×20.2×38.1 | 34kg-cm | 7.4V | Aluminum alloy | 3D aerobatic planes |
Performance Notes:
- Titanium gears (JX CLS-6321HV) resist stripping under shock loads.
- 24V industrial units (e.g., Zanrobot 380kg) are overkill for RC—stick to 8.4V systems.
- Waterproofing servo (HiTec D845WP) prevents salt corrosion in marine environments.
Servo vs. Motor Dimensions Relationship in RC Applications
In RC systems, servo dimensions directly reflect internal motor size and gearbox complexity:
Micro Servos (e.g., 9g SG90): Use 6-10mm coreless motors to fit within 23×12×27mm bodies—ideal for weight-critical drones or 1/36 crawlers.
Standard Servos (40mm class): Contain Φ22-28mm brushed motors (MG996R: Φ25mm) driving 3-stage gearboxes—balanced for 1/10 buggies/touring cars.
High-Torque Servos: Integrate Φ30-35mm brushless motors (e.g., ProModeler DS630BLHV) with titanium gears to achieve 50kg-cm+ torque in 1/5 scales.
Key Insight: Motor diameter dictates servo width—critical for chassis clearance. A 1/10 drift car’s narrow steering bay (≤20mm) won’t fit a 25mm-wide brushless servo.
Key Selection Criteria
Prioritize Torque Margin: Choose servos with 2× the required torque to avoid cogging/stripped gears.
Voltage Match: 6.0V-rated servos (e.g., Blue Bird) may burn out on 2S LiPo (7.4V); use HV servos (e.g., DS-B008-C) instead 17.
Water Exposure: IP66-rated models (OMG ST-20DM) for boats/crawlers 6.
For heavy loads (e.g., crawler winches), select servos with 2× your calculated torque requirement to prevent cogging under strain.
Arm your RC build with precision-matched components. Cross-reference these charts against your model’s manual, measure mounting bays twice, and prioritize gear durability over raw speed for longevity. When in doubt, consult manufacturer sizing tools like ServoDatabase or Hitec’s Servo Center.