For a centered 1 kg object held between two vertical side contacts, a friction coefficient of 0.3 and a margin of 2 give a required normal force of 32.69 N per jaw, or 65.38 N across both jaws, at rest. Use the calculator to change those assumptions and compare a known force per jaw.
This is a friction-grip estimate for two symmetric jaws. It does not select a gripper or evaluate offset loads, finger strength or part damage.
한국어: 그리퍼 파지력 계산기와 해설.
Physical AI LabENGINEERING TOOLSPARALLEL GRIPPER · TWO JAWS
Parallel Gripper Force Calculator
How much force does each jaw need to hold your object? Change the mass, contact friction and upward acceleration to compare the required gripping force.
Object and motion
Symmetric side gripping, a centered load and vertical motion only. Check object damage, eccentric loads, impacts and finger strength separately.
Force with your calculation margin
LIVE CALCULATIONCheck the inputs. Results will return when all values are valid.
Forces on the object
Direction diagram · Arrows not to scaleBlue arrows show inward normal force. Green arrows show friction capacity μN, not the friction force that always acts at the contact.
What if the contact friction changes?
All other inputs stay fixed. Compare 0.5×, 1× and 1.5× your entered coefficient. These are scenarios, not a measurement uncertainty range.
UNDERSTAND THE RESULT
Match the force convention first.
A catalog may report force per jaw or the sum of both jaw forces. Here, the total adds their magnitudes. The opposing normal forces do not add into a net force pushing the object sideways.
Less friction means more normal force is needed to hold the same load. Simply squeezing harder can damage a thin or soft object. This model estimates the force needed against slipping; it does not calculate object damage.
Formula, assumptions and manufacturer reference
Two jaws press inward with equal normal force. Both contacts have the same friction coefficient, and the vertical load is centered between them.
Njaw = S × m × (g + a) / (2 × μ)
N_jaw is normal force per jaw [N], S is your calculation margin, m is object mass [kg], a is upward acceleration [m/s²], and g = 9.80665 m/s². Each contact must support m(g+a)/2; its friction capacity is μN_jaw.
Before applying the margin, the ideal slip threshold is m(g+a)/(2μ). The total gripping-force magnitude is 2N_jaw. An available-force comparison checks your entered assumptions and margin, not the safety of a real device.
This model assumes external side gripping of a rigid, centered load. It excludes rotation, angled or eccentric loads, impacts, post-slip behavior, contact deformation, object damage, finger strength and actuator limits. Verify friction and the actual force at the gripping point.
The example coefficient of 0.3 and margin of 2 are assumed values for comparing behavior. They are not measured values or manufacturer recommendations.
The static force balance and per-finger force convention follow SMC MHF2 · Model Selection. Its product-specific margin, recommended force multiples and gripping-point limits are separate from this generic calculation.
The (g+a) term is a Newton-law extension for upward acceleration. Downward acceleration, horizontal motion and rotation are outside this version’s scope.
The same 1 kg object can need three times the force
These are calculated examples, not measurements from a gripper. All three rows use a mass of 1 kg and a margin of 2; only friction or upward acceleration changes.
| Condition | Friction μ | Upward acceleration | Force per jaw | Two-jaw total |
|---|---|---|---|---|
| At rest | 0.3 | 0 m/s² | 32.69 N | 65.38 N |
| Lower assumed friction | 0.1 | 0 m/s² | 98.07 N | 196.13 N |
| Accelerating upward | 0.3 | 5 m/s² | 49.36 N | 98.71 N |
The calculation is N per jaw = S × m × (g + a) / (2 × μ), with g = 9.80665 m/s². Two contacts share the vertical load. The total shown is the sum of the two opposing normal-force magnitudes, not a net sideways force.
Reducing the assumed friction from 0.3 to 0.1 triples the required squeeze. An upward acceleration of 5 m/s² raises it by about 51% compared with holding the object still. Constant upward speed uses a = 0; braking a downward move can require positive upward acceleration.
Check what the catalog means by gripping force
The SMC MHF2 selection catalog defines its plotted force as one finger’s thrust. The SCHUNK PSH 22-1 series notes use the sum of the individual jaw forces at a specified gripping distance. Those conventions are different: for two equal jaws, a 100 N total means 50 N per jaw.
Use the force available at your actual pressure, finger length and gripping point, rather than a headline maximum. The calculator’s optional comparison accepts force per jaw. Meeting the entered margin does not check allowable moments or whether the object will be crushed.
The initial coefficient 0.3 and margin 2 are illustrative. They are not measured contact properties or a universal recommendation. SMC’s cited MHF2 guidance uses its own margin of 4 and additional selection checks. The upward-acceleration term here is a Newton-law extension of the static force balance.
If the object rotates, check the contact geometry
A part can resist vertical slipping yet rotate because its load is offset or the contacts cannot oppose a moment. The grasp stability and friction-cone guide explains that separate question. For choosing between parallel, vacuum and other gripping approaches, use the gripper selection guide.
Once the grasp is defined, the robot joint still has to support the gripper and object. The robot-arm static torque calculator estimates the gravity torque for that separate load case; jaw force in newtons is not joint torque in newton-metres.
Website analytics and cookies are covered by the site privacy policy.