Thailand is approximately 513,120 sq km, while Bangladesh is approximately 148,460 sq km, making Bangladesh 28.93% the size of Thailand. Meanwhile, the population of Thailand is ~69.0 million people (93.7 million more people live in Bangladesh).
This to-scale map shows a size comparison of Thailand compared to Bangladesh. For more details, see an in-depth quality of life comparison of Bangladesh vs. Thailand using our country comparison tool.