Calculator
Example Data Table
| Mass (kg) | Arm (m) | Gravity (m/s²) | Torque (N·m) |
|---|---|---|---|
| 5 | 0.2 | 9.80665 | 9.8067 |
| 10 | 0.25 | 9.80665 | 24.5166 |
| 15 | 0.3 | 9.80665 | 44.1299 |
| 25 | 0.15 | 9.80665 | 36.7749 |
| 40 | 0.1 | 9.80665 | 39.2266 |
Values assume the force comes from gravity acting on mass.
Formula Used
When you enter mass and arm length:
- F = m × g (force in newtons)
- τ = F × r (torque in newton‑meters)
- Combined: τ = m × g × r
When you enter kgf·m or kgf·cm:
- 1 kgf = g N
- N·m = (kgf·m) × g
- N·m = (kgf·cm) × g ÷ 100
Important: If your “kg” value is not tied to gravity, it cannot become torque alone. Torque needs a force and a lever arm.
How to Use This Calculator
- Select an input type that matches your data.
- Enter the mass and lever arm, or a kgf torque value.
- Keep standard gravity, or set your own value.
- Pick decimal places for clean reporting.
- Click Calculate, then export CSV or PDF if needed.
Article
1) What “kg to N·m” really means
Mass in kilograms does not become torque by itself. Torque is a turning effect, measured in newton‑meters, created by a force acting at a distance. This calculator treats “kg” as a mass that produces weight through gravity, then applies a lever arm. In other words, it converts a practical workshop input into a physics unit.
2) Gravity turns mass into force
The key step is the weight force: F = m × g. Using standard gravity g = 9.80665 m/s², a 10 kg mass produces 98.0665 N of force. If you set g to 9.81, the same mass produces 98.10 N. That small change matters when you are comparing tight torque specs.
3) Mass and lever arm produce torque
Once you have force, torque is τ = F × r, where r is the lever arm in meters. With 10 kg and a 0.25 m arm, τ = 98.0665 × 0.25 = 24.5166 N·m. If the arm is 0.20 m, torque drops to 19.6133 N·m. Doubling the arm doubles torque.
Angle matters too: torque uses the perpendicular component of force. If the load is at 30°, effective torque is τ × sin(30°)=0.5τ. This tool assumes a right‑angle pull, which matches most wrench use. For angled setups, correct your arm length accordingly before calculating.
4) Converting kgf·m to N·m
Some tools rate torque in kilogram‑force meters. One kilogram‑force equals g newtons, so 1 kgf·m equals g N·m. At standard gravity, 7.0 kgf·m becomes 7.0 × 9.80665 = 68.6466 N·m. Changing g changes the definition of kgf in this conversion.
5) Converting kgf·cm to N·m
Kilogram‑force centimeters are common for small fasteners and instruments. First convert centimeters to meters by dividing by 100, then apply kgf to newtons. For example, 85 kgf·cm becomes (85 × 9.80665) ÷ 100 = 8.3357 N·m, which is 833.57 N·cm.
6) Useful ranges and sanity checks
Typical hand screwdriver torques can be 0.5 to 6 N·m, while many automotive lug nuts sit near 80 to 150 N·m. If your result looks 100× too large, check whether you entered cm as m. If it looks too small, confirm you used mass in kg, not force in newtons.
7) Reporting results cleanly
Choose decimal places based on the accuracy of your inputs. A tape measure to the nearest millimeter rarely justifies eight decimals in torque. Use the CSV download for logs and the PDF download for job sheets. Keep the “inputs used” list with the result so others can reproduce the calculation.
FAQs
1) Is kilogram the same as kilogram‑force?
No. Kilogram is mass. Kilogram‑force is weight force created by gravity. This calculator uses your gravity value to convert 1 kgf into g newtons, then reports torque in newton‑meters.
2) Which gravity value should I choose?
Use 9.80665 m/s² for standard calculations and tool specs. Local gravity varies slightly with altitude and latitude, usually changing results by less than one percent. Use a custom value only when you truly need it.
3) Can I convert kg to N·m without a lever arm?
Not from mass alone. Torque needs force and distance. Provide an arm length, or enter a torque already expressed as kgf·m or kgf·cm. Otherwise, the conversion is not physically defined.
4) Why does my torque wrench chart differ from this result?
Charts often assume standard gravity, a perpendicular pull, and rounded arm lengths. If you used cm instead of m, or pulled at an angle, your real torque changes. Match units, gravity, and geometry for consistent numbers.
5) How do I convert N·m back to kgf·cm?
Divide by gravity and convert meters to centimeters. Use: kgf·cm = (N·m × 100) ÷ g. For kgf·m, use kgf·m = (N·m) ÷ g.
6) What is the difference between N·m and N·cm?
They measure the same quantity with different scales. 1 N·m equals 100 N·cm. N·cm is handy for small fasteners, instruments, and calibration work where values under 10 N·m are common.