Australian Capital Territory is about 1.5 times smaller than Long Island.

Long Island is approximately 3,566 km² (1,377 sq mi), while Australian Capital Territory is approximately 2,358 km² (910 sq mi), making Australian Capital Territory 66.12% the size of Long Island.
Tip: This to-scale comparison of Long Island vs. Australian Capital Territory uses the Mercator projection, which distorts the size of regions near the poles.

Compare further: Australian Capital Territory vs. Long Island

Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.