United States is approximately 9,833,517 sq km, while Nigeria is approximately 923,768 sq km, making Nigeria 9.39% the size of United States. Meanwhile, the population of United States is ~332.6 million people (118.6 million fewer people live in Nigeria).
This to-scale map shows a size comparison of United States compared to Nigeria. For more details, see an in-depth quality of life comparison of Nigeria vs. United States using our country comparison tool.