...
As big as Michigan (250,737 sq km):
Ghana, Guinea, United Kingdom
As big as Colorado (269,618 sq km):
Burkina Faso, Gabon, New Zealand, Western Sahara
As big as Nevada (286,367 sq km):
Ecuador
As big as Arizona (295,274 sq km):
Italy, Philippines
As big as New Mexico (314,924 sq km):
Congo (Republic of the), Côte d’Ivoire, Finland, Malaysia, Norway, Oman, Poland, Vietnam
As big as Montana (380,847 sq km):
Germany, Japan, Zimbabwe
As big as California (423,999 sq km):
Cameroon, France, Iraq, Morocco, Papua New Guinea, Paraguay, Spain, Sweden, Thailand, Turkmenistan, Uzbekistan, Yemen
As big as Texas (695,673 sq km):
Afghanistan, Bolivia, Botswana, Central African Republic, Chile, Colombia, Egypt, Ethiopia, Kenya, Madagascar, Mauritania, Mozambique, Myanmar, Namibia, Nigeria, Pakistan, Somalia, Tanzania, Turkey, Ukraine, Venezuela, Zambia
As big as Alaska (1,700,133 sq km):
Algeria, Angola, Chad, Congo (Democratic Republic of the), Greenland, Indonesia, Iran, Libya, Mali, Mexico, Mongolia, Niger, Peru, Saudi Arabia, South Africa, Sudan
Twice as big as Alaska (3,400,266 sq km):
Argentina, India, Kazakhstan
(Added for topical reference: European Union @4.4M km², inc 242k km² of UK, or almost one Michigan)
As big as the United States (9,826,630 sq km):
Australia, Brazil, Canada, China
Twice as big as the United States (19,653,260 sq km):
Russia
I enjoyed doing that. Most of it not relevant, and had to stop myself doing GDPs, but it was both fun and educational. Hurrah!