What this calculator does
Center of mass (two bodies) works out balance point of two masses along a line, and its distance from each. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formular₁ = d·m₂/(m₁+m₂); r₂ = d·m₁/(m₁+m₂), measured from each mass, r₁+r₂ = d
The inputs explained
| Field | What to enter |
|---|---|
| Mass 1 (kg) | A number, measured in kg. Starts at 5.972e+24. |
| Mass 2 (kg) | A number, measured in kg. Starts at 7.342e+22. |
| Separation between the masses (m) | A number, measured in m. Starts at 384400000. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with mass 1
Every other input is held at the calculator’s starting values while mass 1 varies. Select any row to load that scenario into the calculator.
How the answer changes with mass 1
| Mass 1 (kg) | Distance from mass 1 to the center of mass | Distance from mass 2 to the center of mass | Distance from mass 1 |
|---|---|---|---|
| 2,986,000,000,000,000,000,000,000 | 9,224,836 m | 375,175,164 m | 9,225 km |
| 4,479,000,000,000,000,000,000,000 | 6,199,482 m | 378,200,518 m | 6,199 km |
| 5,972,000,000,000,000,000,000,000 | 4,668,435 m | 379,731,565 m | 4,668 km |
| 8,958,000,000,000,000,000,000,000 | 3,124,940 m | 381,275,060 m | 3,125 km |
| 11,944,000,000,000,000,000,000,000 | 2,348,478 m | 382,051,522 m | 2,348 km |
| 17,916,000,000,000,000,000,000,000 | 1,568,847 m | 382,831,153 m | 1,569 km |