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Center of Mass Calculator.

Find the one-dimensional center of mass of two point masses.

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01

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Results update as you type.

Center of mass: 1 m

Center of mass

1.000000m

Results update automatically as you type.

Use Cases

Physics homework and study

Quickly verify your manual calculations for two-mass systems in mechanics or introductory physics courses.

Example: Check the center of mass of a 2 kg mass at 0 m and a 3 kg mass at 4 m.

Engineering design checks

Use it to estimate the balance point of simple two-component systems, such as a seesaw or a beam with two loads.

Example: Find where to place a pivot for a 5 kg load at 1 m and a 7 kg load at 3 m.

Frequently Asked Questions

What is the center of mass?
The center of mass is the point where the total mass of a system can be considered to be concentrated. For two point masses, it's the weighted average of their positions, with weights equal to their masses.
How is the center of mass calculated?
The calculator uses the formula: (m1*x1 + m2*x2) / (m1 + m2), where m1 and m2 are the masses and x1 and x2 are their positions along a line.
What units should I use?
Enter masses in kilograms (kg) and positions in meters (m). The result will be in meters, consistent with the input units.

Tips & Common Mistakes

Tips

  • Ensure both masses are positive; negative masses are not physically meaningful.
  • Positions can be negative if you use a coordinate system with a zero point not at the leftmost mass.
  • The center of mass will always lie between the two positions if both masses are positive.
  • Double-check your units: if you use grams or centimeters, convert to kg and meters first.

Common Mistakes to Avoid

  • Forgetting to convert units to kg and m, leading to incorrect results.
  • Using the average of positions without weighting by mass, which is only correct when masses are equal.
  • Entering positions in different units (e.g., one in meters, one in centimeters) without converting.

Last updated: August 13, 2026