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Servo Motor Calculator

Find the right servo torque for your load, arm length, and speed

Required Torque

5 kg·cm

Safety

2.2x

Power

3 W

Required Torque

5 kg·cm

(69.4 oz·in)

Available

11

Safety

2.2x

Status

OK

Performance

Sweep Time0.51 s
Angular Velocity360\u00B0/s
Est. Current0.5 A
Power Draw3 W

Example Calculations

1500g load at 10cm

Inputs

Load500 g
Arm10 cm

Result

Required Torque5.00 kg·cm
Safety (MG996R)2.2x

500 × 10 / 1000 = 5 kg·cm. MG996R (11 kg·cm) gives 2.2x safety factor.

2200g load at 5cm

Inputs

Load200 g
Arm5 cm

Result

Required Torque1.00 kg·cm
Safety (SG90)1.8x

200 × 5 / 1000 = 1 kg·cm. SG90 (1.8 kg·cm) gives 1.8x safety factor.

Frequently Asked Questions

Q

How do I calculate required servo torque?

Torque (kg·cm) = load weight (g) × arm length (cm) / 1000. A 500g load at 10cm needs 5 kg·cm. Always add a 1.5–2x safety factor.

  • T = weight(g) × arm(cm) / 1000
  • 500g at 10cm = 5 kg·cm
  • Safety factor: 1.5x minimum, 2x recommended
  • 1 kg·cm = 13.889 oz·in
ServoTorqueSpeedUse Case
SG901.8 kg·cm0.1s/60°Micro projects
MG996R11 kg·cm0.17s/60°Standard robots
DS321821 kg·cm0.16s/60°Heavy loads
Q

What safety factor should I use for servo selection?

Use at least 1.5x for static loads and 2–3x for dynamic loads with acceleration. Undersized servos overheat, strip gears, and fail prematurely.

  • 1.5x: static, slow movement
  • 2x: moderate speed, some acceleration
  • 3x: fast motion, impacts, vibration
  • Metal gears handle peak loads better than nylon
Q

How does arm length affect torque requirements?

Torque increases linearly with arm length. Doubling the arm doubles the required torque. Keep arms as short as possible to reduce servo requirements.

  • 10cm arm, 500g = 5 kg·cm
  • 20cm arm, 500g = 10 kg·cm
  • 30cm arm, 500g = 15 kg·cm
  • Shorter arm = less torque needed
Q

What is servo speed measured in?

Servo speed is rated as seconds per 60 degrees at no load. An MG996R at 0.17s/60° takes 0.51 seconds for a full 180° sweep. Load slows the servo further.

  • 0.10s/60° = fast (micro servos)
  • 0.17s/60° = moderate (standard)
  • 0.25s/60° = slow (high-torque)
  • Actual speed decreases under load

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This calculator is provided for informational and educational purposes only. Results are estimates and should not be considered professional financial, medical, legal, or other advice. Always consult a qualified professional before making important decisions. UseCalcPro is not responsible for any actions taken based on calculator results.

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