"Damn, is that actually to scale?," wrote another person.
"Australia is exactly the same width as the USA??," wrote someone else.
"Wholey Crap! It is!! [sic]"
"Australia is as large as the US? Didn't know that," wrote another woman.
"And good lord what is happening, the whole continent truly is burning."
A tweet from ABC News attracted a similar response.
The ABC reported how the raging fires have burned 12.35 million acres (5 million hectares) of land - with at least 24 people killed and more than 2000 homes destroyed by the blazes.
"The size of the fires across the country are twice as large as the state of Maryland and bigger than several other states, including Vermont, New Hampshire, Massachusetts and New Jersey," they wrote.
"A superimposed map of Australia over the United States shows the scale of the regions affected by the massive wildfires that have spread Down Under."
However some reports indicate 5 million hectares of land burned in New South Wales alone, with overall estimates up to 10 million hectares.
Meanwhile scattered showers should continue to fall on fire grounds until midweek as attention turns to getting towns up and running.
In NSW, more than 13mm fell at Merimbula on Monday, 9.8mm at Bega and 2mm at Nowra and Lake Conjola.
In Victoria, the rain that is giving bushfire-hit areas some much-needed relief continued throughout Tuesday.
Monday saw all emergency warnings being downgraded, while 14 active fires continued burning statewide.
There were fears of a "megablaze" forming from three fires along the NSW-Victoria border Tuesday, according to fire chiefs.