Mongolia is approximately 1,564,116 sq km, while Papua New Guinea is approximately 462,840 sq km, making Papua New Guinea 29.59% the size of Mongolia. Meanwhile, the population of Mongolia is ~3.2 million people (4.1 million more people live in Papua New Guinea).
This to-scale map shows a size comparison of Mongolia compared to Papua New Guinea. For more details, see an in-depth quality of life comparison of Papua New Guinea vs. Mongolia using our country comparison tool.