Torque is the twisting force that causes an object to rotate. When you open a door or twist a screw, the force you apply multiplied by the distance from the pivot point creates torque.
For hinges, torque represents the rotational force generated by the lid or door due to gravity. In simple terms:The heavier the lid and the farther its center of gravity is from the hinge, the greater the torque.
Understanding torque helps you choose the correct hinge so the panel does not sag, drop suddenly, or feel too light during closing.
Why Do We Need to Calculate Hinge Torque?
Hinges are widely used in flip-lids and cabinet structures. Examples include:
● Laptop screens – The hinge must provide sufficient torque to balance the weight of the screen.
● Toolbox or cabinet lids – These are often wider and heavier, generating higher torque.
● Industrial equipment doors or appliance lids – Heavy panels require hinges strong enough to prevent unwanted dropping.
If torque is too low, the lid will slam shut.
If torque is too high, the lid becomes difficult to open or feels stiff.
Calculating hinge torque ensures the hinge’s torque rating is higher than the torque generated by the lid, resulting in a smooth and safe user experience.
How to Estimate Torque
The basic principle is: Torque = Force × Distance.
The formula is:
T = F × d
Where:
T = torque (N·m)
F = force (usually the weight of the lid), in Newtons
d = distance from the hinge to the lid’s center of gravity (horizontal distance)
To calculate force:
F = W × 9.8
(W = mass in kg; 9.8 N/kg = gravitational acceleration)
For a uniformly distributed lid, the center of gravity is located at the midpoint (L/2 from the hinge).
Example Calculation
Lid length L = 0.50 m
Weight W = 3 kg
Center of gravity distance d = L/2 = 0.25 m
Step 1:
F = 3 kg × 9.8 N/kg = 29.4 N
Step 2:
T = 29.4 N × 0.25 m = 7.35 N·m
This means the hinge system must provide about 7.35 N·m of torque to counteract the lid’s weight.
If using two hinges, each hinge carries roughly half of the torque.
Conclusion
To estimate the required hinge torque:
● Torque (T) = Force (F) × Distance (d)
● Force comes from the lid’s weight
● Distance is determined by the center of gravity
● Two hinges share the torque load
● Always choose a hinge with torque slightly higher than the calculated value
The above are only fundamental principles. In real applications, additional factors must also be considered when calculating hinge torque. Feel free to contact us, and we can review your project in detail together!
Post time: Dec-17-2025
