| SG90 (micro) | MG996R (standard size) | |
|---|---|---|
| Weight | About 9 g | About 55 g |
| Gears | Plastic | Metal |
| Stall torque (seller figures) | About 1.8 kg·cm at 4.8 V | About 9.4 kg·cm at 4.8 V, 11 kg·cm at 6 V |
| Speed (no load) | About 0.1 s per 60° | About 0.17 s per 60° at 4.8 V |
| Supply | 4.8–6 V | 4.8–7.2 V |
| Current | A few hundred mA moving or stalled | Up to about 2.5 A when stalled |
| Typical price in India | ₹80–150 | ₹300–550 |
Both use the same three wires and the same Servo library code — write(90) means 90° on either. The difference is muscle, and how much current that muscle needs. Torque and speed are typical seller datasheet figures; clones vary widely, especially for the MG996R. Prices are indicative.
SG90: light jobs
- Pointer gauges, small flaps, a dustbin lid, a pan-tilt for a tiny camera, light robot arms.
- One SG90 can run from an Uno’s 5V pin for learning — put a 100–470 µF capacitor across its power leads (day 14 shows the build).
- Plastic gears strip if something forces the arm or it’s stalled for long.
Guides: SG90 with Uno, with ESP32, with Pico W.
MG996R: real loads
- Robot arm shoulders and elbows, steering, door latches, valve handles.
- Metal gears survive knocks far better.
- Never power it from the board. A stall draws amps; the board’s 5V rail collapses and the board resets. Use a separate 5–6 V supply rated 2–3 A per servo (a UBEC, a good 5 V adapter or a buck converter), and join its GND to the board’s GND.
Things that catch people out
- Fake MG996Rs are common. Signs: very light weight, plastic gears visible through the case, jittery hold. Buy from sellers with real reviews.
- “360°” versions are continuous-rotation motors —
write()sets speed and direction, not angle. Check the listing. - Jitter usually means a weak supply or noisy ground, not bad code — see servo jitter.
- On an ESP32, the signal is 3.3 V; most servos accept it directly. Power still comes from 5 V.
The middle option: MG90S
Same size and weight as the SG90 but with metal gears and a little more torque (roughly 2 kg·cm), for about ₹180–300. A good upgrade for small robot arms where SG90 gears keep stripping.
Verdict
| Job | Pick |
|---|---|
| Light pointer, flap, lid, learning | SG90 |
| Small arm that keeps stripping gears | MG90S |
| Heavy arm joint, steering, latch | MG996R with its own supply |
Projects: joystick robot arm, smart dustbin, tilt-controlled servo.