Gravity Calculator

Work out the pull between two masses, or how gravity weakens as you go higher above Earth.

How it works

Newton's rule is F equals G times mass 1 times mass 2, divided by distance squared. G is 6.674 times 10 to the power minus 11. The pull gets four times weaker when the distance doubles, because distance is squared. That is why you feel Earth's pull strongly, but the pull between two people is far too small to notice. For height, gravity is GM divided by (Earth's radius plus height) squared. At the top of Everest it is only a little weaker than at sea level, about 9.79 instead of 9.82, because 8,849 metres is tiny next to Earth's 6,371 kilometre radius. At the space station, 400 kilometres up, it is about 8.7, still most of sea-level gravity, and astronauts float because they are falling around Earth, not because gravity is gone.

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