Canberra is about 1.8 times bigger than Northern Mariana Islands.

Northern Mariana Islands is approximately 464 sq km, while Canberra is approximately 814 sq km, making Canberra 75% larger than Northern Mariana Islands.
Tip: This to-scale comparison of Northern Mariana Islands vs. Canberra uses the Mercator projection, which distorts the size of regions near the poles.