Robot Arm Torque Calculator

The Robot Torque Arm Calculator is intended to help you choose the right motor for each joint of your robotic arm. The torque (T) required at each joint is calculated as a worst case scenario (lifting weight at 90 degrees). Ensure your units are consistent. Most common units are kg-cm and oz-in. Take a look at the Robot Arm Torque Tutorial for more information.

  • L: length from pivot to pivot.
  • M: link mass
  • A: Actuator (servo or other) mass. Note: same units as for link masses.
  • A1: can represent the load being lifted.
Robot Arm Torque CalculatorRobot Arm Torque Calculator

Use the image above to help you determine which torque corresponds to which joint. Note the numbering starts with the extremity of the arm, so the final torque is the one lifting the entire arm (start from A1 being the load you wish to carry at full reach.). The torque shown is the RATED TORQUE you can use for your search. Note that should this be the stall torque, the arm would not be able to lift itself at full extension with a payload.


L: [cm] M: [kg] A: [kg] T: [kg cm]
L1: M1: A1: T1:
L2: M2: A2: T2:
L3: M3: A3: T3:
L4: M4: A4: T4:
L5: M5: A5: T5:
L6: M6: A6: T6:

This is a companion discussion topic for the original entry at

Required this torque calculation for our newly developed Industrial Automation and Robotics Laboratory.
Mohan Kumar S
Asst. Professor
Mechanical Engineering Department
Vidya Vikas Institute of Engineering and Technology
Alanahally 570028 Mysuru - Karnataka - India

How to calculator robot arm

@pieter Not sure what you mean.

thanks a to calculate the torque for a cylindrical robot arm which has one rotary and 2 linear joints

@aishwarya poojary Can you create a new topic on the RobotShop Forum and include an image or drawing of the setup?

Please How accurate is that calculations ?

@Khaled Refer to the tutorial to see which assumptions were made. This is a “worst case” scenario where the arm needs to support an object at maximum reach.

Very insightful. Do you have any ideas about a program that can calculate the torque required to actuate a joint? Thank you.

@Bruno Akinjide Orisanaiye We do not have a specific program, but it’s all a question for force times distance.

please explain how to calculate the required torque for base rotation

@Zeeshan The base rotation only needs to resist inertia and friction. Both of these tend to be hard to calculate, but also relatively low. We do not have any particular method to suggest at this time, but ensure the weight of the arm is not supported directly by an actuator’s output shaft but ideally by bearings.

thanks a lot.Is this torque useful for industrial design?I want to build industrial robot arm and in want to choose my servo motors.
can this help me?

@mohammad The calculations here are a bit simplified, but yes, the calculations can certainly give you an idea of the torque you will need at each joint in order to hold the arm at full reach.

@Coleman Benson , I want formulas for the torque calculation. I am making robotic arm (5 dof). and I don’t know how to calculate torque of base.

@waqas Take a look at the tutorial here:

Can you give me the equation that was used above !?

1 Like

@Abode The equations are in the tutorial:

When are talking about the link mass is multiple by the gravity or just mass?

@Jose Carlos For calculation purchases, you should use a force, not the mass. Force = mass x acceleration (F=m*a). Acceleration in this case is gravity, so the metric units of force would be Newtons.