Local Gravity

Gravity on earth is not constant, it varies due to both altitude and how close to the equator you are. As you get nearer to the equator the spin of the earth is faster which counteracts a small amount of the force gravity imposes.

Using latitude and altitude a more accurate value for g can be found. This application will tell you what the local gravity is at your location, at any latitude and altitude of your choice and at a selection of different locations around the world.