Practical tools for measured work
Tension calculator
Calculate tension for one vertical rope, two supporting ropes or an ideal two-mass pulley.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
How it works
For one vertical rope, T = m(g + a) with upward acceleration positive. For two supporting ropes at angles α and β above horizontal, TL = mg cos(β)/sin(α+β) and TR = mg cos(α)/sin(α+β). For an ideal two-mass pulley, acceleration of mass 2 downward is (m2−m1)g/(m1+m2).
Current-input example
The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.
- Rope configuration
- One vertical rope
- First mass
- 2 kg
- Gravitational acceleration
- 9.80665 m/s²
- Upward acceleration
- 0 m/s²
Primary result: Rope tension: 19.6133 N.
Before using the result
- Check the selected mode, units and input values before using the result.
- Read the assumptions and rounding rules; compare the worked example with your intended calculation.
- A numerical result does not supply missing context or change the stated limitations.
Limitations
Ropes are massless and taut; the pulley is frictionless and massless. Two-rope angles must be strictly between 0° and 90°. Negative required tension is rejected because a rope cannot push. This is not a lifting-equipment or rigging design tool.
Frequently asked questions
Which physical model does this result assume?
Use only the configuration named in the selected mode. Enter consistent SI units and check the stated direction, axis and equilibrium assumptions. These educational ideal models do not certify equipment, structures or lifting arrangements.
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