The power you need really depends on the sort of work you wish to do. Chainsaws range from small, domestic electric machines suitable for chopping small quantities of firewood all the way up to large, high performance saws used by foresters, and even, in some cases, to very powerful professional chainsaws used by emergency and rescue crews. The following is a very rough guide to power requirements.
Smaller Domestic Chainsaws – Electric And Petrol
If you plan to be creating firewood, or pruning shrubs in smaller domestic premises, then an electric chainsaw will probably be ideal. You can use them in enclosed spaces, inside sheds, workshops and garages as they produce no noxious emissions and are lightweight and more easily manoeuvrable in tighter spaces than large petrol chainsaws. They can be used in residential areas, as they are reasonably quiet.
For similar work where mains electricity is not available, and for slightly tougher applications, a smaller petrol chainsaw would be suitable.
With domestic Chainsaws, entry-level machines generally come in at around 35cc or so, moving up through 40cc and 45cc depending on the requirements of the user. 50cc would probably be the top end for domestic purposes.
Medium Sized Semi-Professional Chainsaws – Petrol
These are chainsaws suitable for landscaping or agricultural work. Ideal for limbing, pruning, clearing underbrush and other day to day outdoor tasks, a chainsaw for this kind of work would probably be roughly 40-50cc
Larger, Professional Chainsaws – Petrol
A large, powerful professional chainsaw like this would be needed for regular, rigorous tasks, in large premises, like woodland or big estates.
These would be suitable for felling trees, cutting thick logs or carrying out a lot of heavy work. They are ideal for an pro' arborist with large trees to cut down or limb* or someone who would be using the chainsaw every day for forestry work or creating very large quantities of firewood. These chainsaws can be anything from around 40-45cc* up to 100cc and more.
* Top handle saws - which are used by tree surgeons for limbing work - tend to only be around 35-40cc as they are used up in trees and need to be light. They will only be used for cutting branches .