Indonesia is approximately 1,904,569 sq km, while United Kingdom is approximately 243,610 sq km, making United Kingdom 12.79% the size of Indonesia. Meanwhile, the population of Indonesia is ~267.0 million people (201.3 million fewer people live in United Kingdom).
This to-scale map shows a size comparison of Indonesia compared to United Kingdom. For more details, see an in-depth quality of life comparison of United Kingdom vs. Indonesia using our country comparison tool.