Self-contained rotary actuators with built-in motor, gearbox, and position feedback — the default joint drive for hobby, edu, and many light-duty robot builds.
A packaged rotary actuator: motor, reduction gear, control board, and potentiometer or encoder feedback in one housing, commanded to hold a target angle.
Think of a servo as a motor that knows its angle and goes to the position you ask for — like telling a door hinge to stop at 45° and stay there even if someone pushes on it (within its torque limit).
The control loop compares commanded pulse width or serial setpoint to measured position, driving H-bridge outputs until error is minimized. Stall torque, gear ratio, and supply sag define whether the joint holds under load or buzzes and overheats.
Rotates an output horn to a commanded position and holds torque against load — the basic joint for RC-style arms, pan/tilt heads, grippers, and competition robots.
Potentiometer feedback, PWM input — lowest cost; plastic gears common.
MCU on servo board; faster loop; often better holding torque.
2S-compatible — less current for same power; popular on larger RC rigs.
Bus-addressable, telemetry, metal gears — research and edu platforms.
Separate motor + drive — not a hobby brick; see actuators component page.
SKU-level comparison is not available yet — use this table to decide what to verify before ordering.
14 selection specs · 8 key for buying decisions
| Spec | Why it matters | Buyer warning |
|---|---|---|
Torque (stall / rated) kg·cm or N·m Key selection spec ~0.15–20+ kg·cm hobby; higher industrial | Must exceed worst-case joint load including arm length. Beginner: Think kg·cm at the horn — longer arms multiply effective load. Advanced: Convert joint moment to required stall torque including acceleration torque. | Size for peak load with acceleration, not static weight alone. |
Speed s/60° Optional detail Often 0.1–0.2 s/60° hobby | Cycle time and settling on multi-axis moves. | Faster often trades torque in same size class. |
Voltage V Key selection spec 4.8 V, 6.0 V, 7.4 V, 8.4 V common | Wrong voltage damages servo or reduces torque. Beginner: Higher voltage often means more torque but only if the servo is rated for it. Advanced: Bus sag under stall can dip below minimum operating voltage. | Match pack/BEC to datasheet — not just '5 V'. |
Stall current A Key selection spec Hundreds of mA idle; amps at stall | Power supply and wire gauge must survive stall. Beginner: Stall current is the worst case — size power for it, not idle draw. | Undersized BEC causes brownouts. |
No-load current A Optional detail | Baseline heat and battery runtime. | Idle draw adds up on multi-servo buses. |
Size class Key selection spec 9 g micro, standard 45–55 g, 1/4-scale | Physical fit and gear strength. | Micro servos strip on arm loads. |
Rotation range ° Key selection spec Often ~180° hobby | Joint limits vs continuous rotation needs. | Continuous rotation is speed control, not position hold. |
Gear material Key selection spec Plastic, karbonite, metal | Shock load survivability. | Plastic strips under binding or shock. |
Feedback type Optional detail Potentiometer, encoder | Resolution, backlash, bus telemetry. | Pot wear causes jitter on old hobby units. |
Control signal Key selection spec PWM 50 Hz; TTL/RS-485 serial | Must match controller outputs and libraries. Beginner: PWM hobby servos use one signal wire plus power — smart servos use a bus. Advanced: Half-duplex TTL timing and baud rate must match entire daisy chain. | Verify PWM vs serial before bulk order. |
Duty cycle / thermal Optional detail | Continuous holding overheats cheap servos. | Intermittent-rated units fail under constant load. |
Waterproofing / IP Optional detail | Outdoor and washdown environments. | Most hobby servos are not sealed. |
Connector type Key selection spec JR, Futaba, JST; bus-specific on smart servos | Harness compatibility and pin current capacity. | Wrong connector causes intermittent faults. |
Mounting pattern Optional detail | Mechanical integration to horn and bracket. | Verify horn spline and screw pattern. |
Torque (stall / rated)
kg·cm or N·m
~0.15–20+ kg·cm hobby; higher industrial
Must exceed worst-case joint load including arm length.
Size for peak load with acceleration, not static weight alone.
Beginner: Think kg·cm at the horn — longer arms multiply effective load.
Advanced: Convert joint moment to required stall torque including acceleration torque.
Speed
s/60°
Often 0.1–0.2 s/60° hobby
Cycle time and settling on multi-axis moves.
Faster often trades torque in same size class.
Voltage
V
4.8 V, 6.0 V, 7.4 V, 8.4 V common
Wrong voltage damages servo or reduces torque.
Match pack/BEC to datasheet — not just '5 V'.
Beginner: Higher voltage often means more torque but only if the servo is rated for it.
Advanced: Bus sag under stall can dip below minimum operating voltage.
Stall current
A
Hundreds of mA idle; amps at stall
Power supply and wire gauge must survive stall.
Undersized BEC causes brownouts.
Beginner: Stall current is the worst case — size power for it, not idle draw.
No-load current
A
Baseline heat and battery runtime.
Idle draw adds up on multi-servo buses.
Size class
9 g micro, standard 45–55 g, 1/4-scale
Physical fit and gear strength.
Micro servos strip on arm loads.
Rotation range
°
Often ~180° hobby
Joint limits vs continuous rotation needs.
Continuous rotation is speed control, not position hold.
Gear material
Plastic, karbonite, metal
Shock load survivability.
Plastic strips under binding or shock.
Feedback type
Potentiometer, encoder
Resolution, backlash, bus telemetry.
Pot wear causes jitter on old hobby units.
Control signal
PWM 50 Hz; TTL/RS-485 serial
Must match controller outputs and libraries.
Verify PWM vs serial before bulk order.
Beginner: PWM hobby servos use one signal wire plus power — smart servos use a bus.
Advanced: Half-duplex TTL timing and baud rate must match entire daisy chain.
Duty cycle / thermal
Continuous holding overheats cheap servos.
Intermittent-rated units fail under constant load.
Waterproofing / IP
Outdoor and washdown environments.
Most hobby servos are not sealed.
Connector type
JR, Futaba, JST; bus-specific on smart servos
Harness compatibility and pin current capacity.
Wrong connector causes intermittent faults.
Mounting pattern
Mechanical integration to horn and bracket.
Verify horn spline and screw pattern.
Additional key specs (seed data)
Typically ~0.15–20+ kg·cm hobby; industrial higher
Must exceed worst-case load at the joint including arm length and acceleration.
Often 0.1–0.2 s/60° hobby; slower = more torque often
Cycle time and settling behavior on multi-axis moves.
Common: 4.8 V, 6.0 V, 7.4 V, 8.4 V — model-specific
Wrong voltage damages servo or reduces torque; verify datasheet.
Hundreds of mA idle; amps at stall
Undersized BEC or USB power causes brownouts and resets.
Micro, standard, high-torque, 1/4-scale, etc.
Physical fit and gear strength — micro servos strip under arm loads.
Often ~180° hobby; continuous rotation variants exist
Wrist and joint limits; continuous rotation is speed control not position.
Plastic, karbonite, metal
Plastic strips under shock loads; metal adds weight and cost.
Potentiometer (hobby), encoder (smart/industrial)
Resolution, backlash, and bus telemetry for tuning.
PWM 50 Hz; TTL serial; RS-485 Dynamixel-style
Must match controller board outputs and libraries.
Intermittent vs continuous rated
Holding heavy loads continuously overheats cheap hobby servos.
Usually none on hobby; some industrial sealed
Outdoor and washdown robots need rated enclosures.
JR, Futaba, JST; smart bus connectors vary
Harness compatibility and current capacity of pins.
Prices vary by model, supplier, quantity, availability, and shipping speed. EAR pricing bands are guidance only unless tied to a sourced product record. Verify current pricing before ordering.
hobby_basic
Plastic-gear hobby servos dominate low-cost kits. Price spreads widely by torque class, gear material, and seller — EAR has not tied this band to verified listing snapshots.
Typical buyer
STEM kits, small rovers, light pan/tilt, low-load joints.
Examples
9 g–17 g class plastic-gear servos, standard 3-pin PWM hobby units.
What affects cost
Price usually excludes
Buyer caution
Source basis
Category-level qualitative guidance — no SKU-linked distributor band yet.
Open research gaps
Verify current pricing with supplier before ordering.
hobby_prosumer
Metal-gear and higher-torque hobby servos step up in cost with gear train, bearings, and heat handling. Prosumer robotics arms often land here before industrial bus servos.
Typical buyer
Competition robots, heavier hobby arms, RC-scale load-bearing joints.
Examples
High-torque metal-gear PWM servos, larger form factors with horn kits.
What affects cost
Price usually excludes
Buyer caution
Source basis
Category-level qualitative guidance — no SKU-linked distributor band yet.
Open research gaps
Verify current pricing with supplier before ordering.
smart_bus
Serial/CAN smart servos add controller electronics, telemetry, and daisy-chain wiring. Per-unit cost rises with torque, feedback, and ecosystem lock-in.
Typical buyer
Humanoid hobby stacks, multi-DOF arms, teams standardized on one bus ecosystem.
Examples
Dynamixel-class, Feetech serial, CAN smart servos with ID addressing.
What affects cost
Price usually excludes
Buyer caution
Source basis
Category-level qualitative guidance — no SKU-linked distributor band yet.
Open research gaps
Verify current pricing with supplier before ordering.
industrial
Industrial servo motors, drives, and gearheads are quoted per axis with engineering support. List pricing is often quote-only; bands require authorized distributor or OEM records.
Typical buyer
Factory automation, cobot OEMs, machine builders replacing axis modules.
Examples
Servo motor + drive packages, integrated gearmotors, cobot joint modules.
What affects cost
Price usually excludes
Buyer caution
Source basis
Category-level qualitative guidance — no OEM or distributor band verified in EAR.
Open research gaps
Verify current pricing with supplier before ordering.
Representative product records for orientation — not endorsements.
EAR compatibility guidance is category-level unless a specific product record is sourced. Always verify voltage, current, connectors, signal type, documentation, and manufacturer limits before ordering.
Build chains
Works with
Required companion parts
Optional companion parts
Common interfaces
Voltage / current / power
Software & controller
Mechanical
Buyer mismatch warnings
Emergency substitution notes
Open research gaps
Full cross-component view: Compatibility overview
EAR does not currently verify live stock or delivery speed. Use this guide to avoid ordering the wrong part, then verify stock, shipping, compatibility, and datasheets with the supplier before purchase.
Urgency summary
Before rush-ordering a servo for a robot arm, lock voltage, torque, control protocol, connector, and power capacity — get any one wrong and the rush order fails even if it arrives fast.
Check stock and shipping live before ordering.
Urgent questions
Acceptable substitutions (category-level)
Dangerous substitutions
Suppliers to check first
Local pickup targets (verify stock)
Marketplace cautions
Before you order
After arrival — bench test
If you get it wrong
Open research gaps
PWM servos need a board that generates 50 Hz pulses with sufficient resolution; smart servos need the correct baud rate, protocol, and daisy-chain power budget. Always budget a separate high-current rail for multiple servos — not the MCU 5 V pin.
7 manufacturers tracked — expand for chips and dossier links.
EAR does not currently show live inventory. Always verify stock, shipping speed, compatibility, and authorized-channel status before ordering.
Start with robotics specialists for hobby and smart servos. Use authorized distributors for industrial smart servo SKUs. Marketplaces require seller and model verification.
Check first
Also check
Use with caution
Supported categories
Likely category source for hobby servos and motor driver modules
Buyer caution
Supplier target — hobby servos and drivers
Supported categories
Likely category source for servos and motion hardware
Buyer caution
Supplier target — competition and actuator channels
Supported categories
Broad robotics catalog in one place
Buyer caution
Shipping verification needed
Supported categories
Likely category source for Dynamixel-class smart servos and actuator modules
Buyer caution
Supplier target — Dynamixel lines
Supported categories
Curated edu/hobby boards with tutorials
Buyer caution
Supplier target — edu/hobby
Supported categories
Well-documented boards and drivers
Buyer caution
Supplier target — edu/hobby
Supported categories
Broad authorized catalog for semiconductors and modules
Buyer caution
Industrial smart servo SKUs — verify stock
Supported categories
Wide semiconductor and module selection
Buyer caution
Shipping verification needed
Supported categories
Fast shipping sometimes available on Prime listings — not guaranteed
Buyer caution
Marketplace — counterfeit risk; verify seller
Browse all suppliers in the Supplier Directory. See what works together in the Compatibility Matrix.
Overnight availability needs live supplier verification. EAR does not track live inventory.
STOCK & SHIPPING
Overnight availability: needs live supplier verification. EAR does not track live inventory.
For rush-order decision checklists, see Emergency sourcing guide above.
Likely supplier targets to check first
See Who sells it above for supplier targets and sourcing guidance — then verify stock and shipping live before ordering.
Emergency sourcing checklist
Gear strip under shock load or binding linkage
Replacement parts risk
Hobby servo gears and pots are often not sold separately — plan full unit spares. Smart servos may offer repair kits from OEM.
Size torque for peak load including acceleration, not static weight alone. Budget power for stall current. Match control protocol to your controller before bulk ordering.
Size torque for peak load including acceleration, not static weight alone. Budget power for stall current. Match control protocol to your controller before bulk ordering.
Sourced USD ranges by servo class
CURRENT STATUS
Qualitative only
NEXT EVIDENCE TARGET
Distributor listings for reference SKUs
Overnight ship verification
CURRENT STATUS
Not live-checked in EAR
NEXT EVIDENCE TARGET
Supplier API or manual spot-check workflow
Controller compatibility matrix
CURRENT STATUS
Partial — board page seeded
NEXT EVIDENCE TARGET
PWM channel count and serial bus maps
These are representative product records and product families for orientation. EAR does not currently verify live stock, current pricing, or final compatibility. Always verify datasheets, supplier stock, and manufacturer limits before ordering.
ROBOTIS·Dynamixel XL / XM
Representative record — not an EAR endorsement or buying recommendation.
Serial smart servos with feedback — common in research arms and humanoid hobby stacks. Multiple models within XL and XM tiers.
BEST-FIT USE CASE
Multi-DOF arms, pan/tilt with telemetry, projects standardized on Dynamixel protocol.
KEY SPECS (SUMMARY)
Price: needs sourced record — verify with supplier
Availability needs live check with supplier before ordering.
SUPPLIER TARGETS
Supplier targets are starting points, not guaranteed sellers or live stock.
Category-level: requires Dynamixel-compatible controller and separate power rail. Model-specific horn, voltage, and protocol version must match your bus.
VERIFY BEFORE BUYING
OPEN RESEARCH GAPS
Pololu·Maestro
Representative record — not an EAR endorsement or buying recommendation.
USB PWM servo controller — companion product for multi-servo hobby setups, not a servo itself.
BEST-FIT USE CASE
Offloading PWM servo control from a host PC or SBC when you already selected compatible hobby servos.
KEY SPECS (SUMMARY)
Price: needs sourced record — verify with supplier
Availability needs live check with supplier before ordering.
SUPPLIER TARGETS
Supplier targets are starting points, not guaranteed sellers or live stock.
Hitec·Hitec RC / hobby servos
Representative record — not an EAR endorsement or buying recommendation.
Established hobby PWM servo line — metal and plastic gear tiers across RC and robotics hobby use.
BEST-FIT USE CASE
RC-scale robotics, pan/tilt, light load-bearing joints with standard PWM control.
KEY SPECS (SUMMARY)
Price: needs sourced record — verify with supplier
Availability needs live check with supplier before ordering.
SUPPLIER TARGETS
Supplier targets are starting points, not guaranteed sellers or live stock.
Savox·Savox high-torque RC/prosumer
Representative record — not an EAR endorsement or buying recommendation.
High-torque hobby/prosumer PWM servos — common upgrade path from plastic-gear hobby units.
BEST-FIT USE CASE
Heavier hobby arms, competition robots, load-bearing joints needing more torque than basic hobby class.
KEY SPECS (SUMMARY)
Price: needs sourced record — verify with supplier
Availability needs live check with supplier before ordering.
SUPPLIER TARGETS
Supplier targets are starting points, not guaranteed sellers or live stock.
Various / clone market·MG996R-style metal-gear hobby
Representative record — not an EAR endorsement or buying recommendation.
Ubiquitous low-cost metal-gear hobby servo class — high variance in quality, torque, and electronics.
BEST-FIT USE CASE
STEM demos, light loads, budget prototypes where failure cost is low.
KEY SPECS (SUMMARY)
Price: needs sourced record — verify with supplier
Controls PWM hobby servos — does not convert protocols. Servo voltage and stall current still need separate supply.
VERIFY BEFORE BUYING
OPEN RESEARCH GAPS
Category-level PWM hobby servo — match voltage, torque, and connector to controller and load.
VERIFY BEFORE BUYING
OPEN RESEARCH GAPS
Category-level — stall current and voltage must match power plan; not interchangeable by footprint alone.
VERIFY BEFORE BUYING
OPEN RESEARCH GAPS
Category caution record — not an EAR recommendation. Verify stall torque and electronics before load-bearing use.
VERIFY BEFORE BUYING
OPEN RESEARCH GAPS