What fraction of the radius is taken up by the chromosphere?

The chromosphere is a thin layer of the Sun's atmosphere, situated above the photosphere and below the transition region. It typically extends about 2,000 to 3,000 kilometers in thickness. Given that the Sun's radius is approximately 696,340 kilometers, the chromosphere occupies a small fraction of the radius, roughly 0.0029 to 0.0043, or about 0.29% to 0.43% of the solar radius.