Macro photography has to do with the size that your subject is projected onto your camera’s sensor. If you have a one-inch subject, its projection at 'life-size' would be one inch on the camera’s sensor. An object which fills one inch of the sensor will fill most of the resulting photo, since the sensors in typical DSLRs are no more than 1.5 inches long.
When an object is projected at life-size onto the sensor, it is at '1:1 magnification'. If an object is projected at half of life-size (say, that one-inch object takes up just 1/2 inch of the sensor), it is at 1:2 magnification. With 1:10 magnification or smaller, you aren’t really shooting a macro photo anymore.