Altitude is the measurement of the vertical distance between sea level and the point of interest. Altitude has traditionally been measured using an altimeter, a device containing mercury that changes volume, like a thermometer, depending on altitude. However, today all you need to get an accurate idea of the altitude of your house is a computer with Internet access. Google Earth has a map of the entire earth, complete with altitudes.
Download Google Earth (earth.google.com). Google Earth is free, and you can load it easily by following the on-screen instructions.
Load the program and type your full address into the search bar. You can find the search bar in the top of the screen labelled: search address. Hit the search button and the map should show your house on the screen.
Move your mouse to mouse over your house in the map. The altitude of your house will appear at the bottom of your screen.