Comparing SG90, MG90S, and MG996R Servo Motors

Servo motors are a staple in robotics, electronics, and hobby projects. They offer precise control over angular position, making them ideal for applications like robotic arms, pan-tilt camera mounts, and small automated mechanisms. If you’re choosing between popular servo models like the SG90, MG90S, and MG996R, this guide will help you understand their differences, applications, and how they compare to stepper motors. Example of other servo motors available can be found on our servo collection page

What is a Servo Motor?

A servo motor is an electromechanical device that converts electrical signals into precise angular motion. Unlike standard DC motors, which rotate continuously when power is applied, servo motors include a feedback system to control position. This makes them perfect for tasks where exact movement is required.

Servo motors are typically controlled via a pulse-width modulation (PWM) signal, which tells the servo what angle to move to. For hobby electronics, this control usually comes from a microcontroller or development board, such as an Arduino or Raspberry Pi.

Unlike a standard DC motor, you cannot simply connect a servo to a battery and expect controlled movement. They require a controller to send the PWM signal and, in many cases, a motor driver to safely handle current if the servo draws more than the microcontroller can provide.

SG90 Micro Servo

The SG90 micro servo is one of the most common micro servos used in electronics and robotics. Its features include:

Size: Small and lightweight
Torque: Approximately 1.8 kg·cm
Rotation: 180°
Voltage: Typically 4.8–6V

The SG90 is ideal for lightweight projects such as small robotic arms, pan-tilt mechanisms for cameras, or simple RC applications. Its lightweight design makes it easy to mount and integrate into compact projects.

MG90S Metal Gear Servo

The MG90S metal gear servo is similar in size to the SG90 but comes with metal gears for increased durability and torque:

Size: Micro
Torque: Approximately 2.2 kg·cm
Rotation: 180°
Voltage: 4.8–6V
Gear type: Metal (better wear resistance than plastic gears)

The metal gears allow the MG90S to handle more demanding tasks without stripping gears under load. This makes it ideal for robotics projects that involve repeated or heavier movements, such as mini robotic arms or lightweight grippers.

MG996R Servo Motor

The MG996R high torque servo is a full-size servo designed for more robust applications:

Size: Standard
Torque: Approximately 9–10 kg·cm at 6V
Rotation: 180°
Voltage: 4.8–7.2V
Gear type: Available in metal & plastic

The MG996R is available in both metal and plastic variants. The metal version is more common and preferred due to its durability and higher torque capabilities, making it suitable for larger robotic arms, RC cars, planes, and other projects that require significant force. The plastic version, while lighter and good for precise movements, has lower torque specs and cannot handle as heavy mechanical loads. For this guide, we will be referring to the metal version.

For a slightly older variant, the MG995 servo motor offers similar performance but may have minor differences in speed and torque.

How do they Compare - SG90 vs MG90S vs MG996R

While the SG90, MG90S, and MG996R all operate using the same PWM control method and offer similar positional accuracy, they differ significantly in strength, size, and durability. The SG90 is best suited to very lightweight tasks where space and cost matter most. The MG90S improves on this by using metal gears, allowing it to handle repeated motion and slightly higher loads without sacrificing its compact form. The MG996R is designed for demanding applications that require much higher torque and physical strength, making it suitable for larger mechanical systems. Choosing between them comes down to balancing torque requirements, physical size constraints, and how much mechanical stress the servo will experience over time.

Dimensions

The SG90 and MG90S are both micro servos and generally share the same physical dimensions, which means they can usually be swapped without changing mounts or brackets. The MG90S uses metal gears, but this does not significantly change its overall size compared to the SG90. In contrast, the MG996R is a standard size servo and is noticeably larger due to its higher torque output, stronger motor, and heavier internal gearing, which require a bigger casing.

SG90 / MG90S Servo Dimensions

MG996R Servo Dimensions

Understanding Rotation: 180° vs 360°

Most common hobby servos, including the SG90, MG90S, and MG996R, usually have a limited rotation of 180°. This means they can rotate from one end to the other but cannot spin continuously. The PWM signal controls the exact angle between 0° and 180°.

Some less common servos offer 360° continuous rotation, which effectively turns them into a controlled DC motor. In this case, the PWM signal controls speed and direction rather than position. Continuous rotation servos are useful for wheels or conveyor belts but are not suitable for precise angular positioning tasks.

Why Use a Motor Driver?

A servo motor driver is an essential component when working with higher-torque servos like the MG996R. Microcontrollers such as Arduino boards can only supply a limited amount of current (typically 20–40 mA per pin), whereas servos often draw hundreds of milliamps or more under load.

A motor driver:

Provides sufficient current to the servo without overloading the microcontroller
Protects the controller from voltage spikes and back EMF
Allows control of multiple motors from a single board

Controlling a Servo

To operate a servo, a development board is required to generate the PWM signal. Common boards include Arduino, Raspberry Pi, ESP32, and similar microcontrollers. These boards allow you to:

Set the desired angle of the servo
Control multiple servos simultaneously
Integrate sensors and feedback for automated systems

Unlike stepper motors or DC motors, servos rely on a control signal to achieve precise movement. Without a development board, you won’t be able to control the position accurately.

Servo vs Stepper Motor

Stepper motors are another option for precise motion control. Unlike servos, stepper motors rotate in discrete steps and can perform full rotations without limits.

Key differences:

Precision: Both stepper motors and servos offer precise positioning, but steppers excel in applications requiring multiple full rotations.
Torque: Servos provide high torque at low speed with feedback, whereas steppers can lose torque at higher speeds.
Control complexity: Servos require PWM signals and feedback to control position, while stepper motors can be controlled with simple step pulses but require more complex driver circuitry for smooth motion.
Applications: Servos are ideal for applications requiring angular positioning, like robotic arms or pan-tilt mounts. Stepper motors are used in 3D printers, CNC machines, and automated sliders.

Choosing the Right Servo

Choosing between the SG90, MG90S, and MG996R depends on your project requirements:

SG90: Lightweight, low torque, low-cost micro projects
MG90S: Micro servo with metal gears for moderate torque and durability
MG996R: High torque, standard size, suitable for larger or heavier projects

If your project requires continuous rotation or very high torque, consider stepper motors or larger servo models.

Practical Tips for Using Servos

Check torque requirements: Ensure your servo can handle the mechanical load to avoid stalling or gear stripping.
Provide adequate power: High-torque servos can draw more current than a microcontroller can supply. Use a separate power source with proper grounding.
Use a motor driver if needed: Protect your board and ensure smooth motion.
Consider rotation type: Standard 180° servos are for angular positioning. Continuous rotation servos act like DC motors for wheels or belts.
Test with small loads first: Especially for micro servos like the SG90 and MG90S, avoid heavy loads that can damage gears.

Servo motors like the SG90, MG90S, and MG996R are versatile components in robotics and electronics projects. By understanding their differences in size, torque, gear type, and rotation, you can select the best option for your needs. While stepper motors offer alternatives for continuous rotation and high-precision applications, servos remain the go-to choice for precise angular motion in compact systems.

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