How to use the center of mass calculator
Find the center of mass position of two point masses. Enter mass 1, position 1, mass 2, position 2 in the fields above; the center of mass, reduced mass are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- m1 — Mass 1 (kg)
- x1 — Position 1 (m)
- m2 — Mass 2 (kg)
- x2 — Position 2 (m)
Worked example
With mass 1 = 3 kg, position 1 = 0 m, mass 2 = 7 kg, position 2 = 10 m, the calculator gives center of mass ≈ 7 m; reduced mass ≈ 2.1 kg.
Frequently asked questions
What is the formula for the center of mass calculation?
Center of mass (m) = (m1 × x1+m2 × x2) / (m1+m2). Reduced mass (kg) = m1 × m2 / (m1+m2). Here m1 is mass 1 (kg), x1 is position 1 (m), m2 is mass 2 (kg), x2 is position 2 (m).
What inputs do I need for the center of mass calculator (2 masses) calculator?
You need mass 1 in kg, position 1 in m, mass 2 in kg, position 2 in m. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.