A 3.5 t mini excavator fits through a garden gate; a 20 t machine moves a basement in a week. Match machine size to access, depth and soil.
Start with access: measure gates and the route to the dig. Then consider dig depth and reach, the volume of spoil and where it goes. Small machines with a hydraulic thumb and a good set of buckets handle most residential work, while bulk excavation pays back the larger machine quickly.