What size is really the wrong question to ask. What you should really ask given what I need in a laptop what is the smallest possibility that fits within my budget. There are three categories that laptops are generally lumped into. These are Ultralights, Standard Laptops, and Desktop Replacements and in the following dections we'll review the benefits and drawbacks of each.


Ultralights
Example:


Benefits:

Size: These laptops can weight under 4 pounds and often have a very small footprint (the footprint being the area it takes up on a desk).
Speed: Ironically even though they're tiny a good number of these laptops are also fairly fast. This is due to the fact that they using top of the line mobile processors.
Battery Life: Again, since they're using top of the line mobile processors these laptops also have excellent battery life (sometimes pushing upwards of 10 hours of usage on a charge)

Drawbacks

Size: Ironically the size of these laptops is also a drawback. The screens are often miniscule and the keyboards hard to type on
Lack of Features: Their small form limits the number of features a manufacturer can include (sometimes they even lack an optical drive).
Price: Be prepared to pay out the nose.

Standard

As you probably guessed this is the catchall category for laptops that aren't lightweights or heavyweights. There is a lot of variety here.
Example:


Benefits:

Price: Since these are mainstream notebooks they often run at sub one-thousand dollar prices
Weight: Although not as mobile as an ultralight you can still take these laptops on your travels (although not recommended if you constantly travel, that's why they make ultralights).
Usability: Monitors are usually 15 inches and the keyboards are almost full size. This means this category of laptops avoids the ergonomic difficulties associated with the tiny ultralights.

Drawbacks:

Battery Life: Although battery life is improving laptops in this category usually only get a few hours before they must be recharged.
Performance: These laptops usually use the slightly lower end mobile processors And so there performance often lags behind that of the ultralights and desktop replacements.


Desktop Replacements

Example:




Benefits:

Performance: As the name suggests these laptops perform at almost the same level as their desktop equivalents (they typically benchmark a bit slower)
Screen Size: These behemoths often have 17inch monitors which makes movie watching a pleasure
Features: Manufacturers take a kitchen sink philosophy when adding features to these laptops and they often include DVD-RWs, plentiful memory and so forth
Gaming: At the time of this writing, desktop replacements are the only class of laptops that regularly have dedicated video cards (the alternative is integrated video which is far slower). This means that you can play your favorite FPS.

DrawBacks: Weight and Footprint: These laptops are big and your back will remind you of that fact if you lug these around too much. Ten pounds might not sound like much but it wears on you.

Conclusion:

None of these types are superior to the others, all have benefits and drawbacks. The point is to select the type of laptop that best suits your needs and your budget.