Minimum? Anything. If you can only get a 60cm up you will struggle more than 80cm, but you will still be able to watch stuff. There is nothing hardly in price between them. An 80cm does not look much bigger than a 60cm, you might think an 80cm is a third bigger than a 60cm. However, what we are interested in is area because it is the area that reflects the signal, and an 80cm is almost twice the area of a 60cm one, even though it is only a third bigger. Because we live in a digital age, we have what is called a "digital cliff". That means the difference between getting a crystal clear picture and no picture at all is small. So you may find you will get some crystal clear pictures with 80cm and yet not get them at all with the 60cm. The other thing is, you actually see a ton of 80cm dishes about. Add in the optical illusion that an 80cm dish does not really look almost twice the area of a 60cm and most people will not notice unless they are side by side brings me to the conclusion... I would say go for the 80cm minimum.