India, with a GDP of $4.19 trillion, surpassed Japan to become the world's fourth-largest economy. Indian economy is now behind only three countries- US, China and Germany. While US' GDP is $30.51 trillion, China and Germany's GDPs are $19.23 trillion and $4.74 trillion, respectively, according to IMF. NITI Aayog said India can become the third largest economy in 2-3 years.