Biomechanical Force Calculator

Calculate joint forces, moments, muscle force, compressive force, and shear force during movement for biomechanical analysis.

Inputs

Body Mass (kg)

Segment Length (cm)

Joint Angle (degrees)

Angular Velocity (deg/s)

External Load (kg)

Tab to move between fields

Results

Joint Reaction Force

102.52 N

Joint Moment17.6 N·m

Estimated Muscle Force352 N

Compressive Force100.55 N

Shear Force251.45 N

How to Use This Calculator

Enter the body segment mass in kg (e.g., forearm = ~1.5 kg).
Enter the segment length in cm.
Input the joint angle in degrees from the reference position.
Enter the angular velocity in rad/s if modeling dynamic movement.
Review the joint reaction force and moment outputs for ergonomic or rehabilitation analysis.

How the result changes with Body Mass (kg)

Body Mass (kg)	Joint Reaction Force
38	76.61 N
83	108.12 N
137	145.93 N
182	177.43 N

What each input means

Body Mass (kg): Total body mass. Segment mass is estimated as a proportion.
Segment Length (cm): Length of the body segment being analyzed (e.g., forearm, thigh).
Joint Angle (degrees): Angle of the joint. 0 = fully extended, 90 = right angle, 180 = fully flexed.
Angular Velocity (deg/s): Speed of joint rotation in degrees per second.
External Load (kg): Mass of any external load (dumbbell, tool, etc.) held by the segment.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Body Mass (kg) = 75, Segment Length (cm) = 35, Joint Angle (degrees) = 90, Angular Velocity (deg/s) = 60 = 5 input(s) provided
Calculate Joint Reaction Force
Joint Reaction Force
102.52 = 102.52
Calculate Joint Moment
Joint Moment = abs(jointMomentNm)
17.6 = 17.6
Calculate Estimated Muscle Force
Estimated Muscle Force
352 = 352

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