太阳半径是天文学中的长度单位，使用目前太阳的半径为基准来表示恒星大小：

太阳的半径大约是695,500 公里（432,450英里）或大约地球半径的110倍，或是木星平均半径的10倍。 由于自转的缘故，从极点至赤道的半径有些微的差异，它的扁率约为十万分之一。相似的长度请参见京米。

在2003年和2006年，SOHO太空船利用水星从太阳表面的前方经过的水星凌日时间测量太阳的半径。测量太阳半径的结果是696,342正负65公里（432,687正负40英里）。

Solar radius is a unit of distance used to express the size of stars in astronomy. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3:

The solar radius is approximately 695,700 kilometres (432,288 miles), which is about 10 times the average radius of Jupiter, 110 times the radius of the Earth, and 1/215th of an astronomical unit, the distance of the Earth from the Sun. It varies slightly from pole to equator due to its rotation, which induces an oblateness in the order of 10 parts per million. (See 1 gigametre for similar distances.)