The size of wires, both solid and stranded, is defined by its gauge.
American wire gauge (AWG), also known as the Brown & Sharpe wire gauge, is a standardized wire gauge system used since 1857 predominantly in North America for the diameters of round, solid, nonferrous, electrically conducting wire.
(Source -
Wikipedia - American wire gauge.)
The larger the gauge number, the smaller the wire. Solid 16 AWG wire is 0.0508" in diameter while 10 AWG wire is a little more than double that, at 0.1019" in diameter.
AWG gauges are also used to describe stranded wire. In this case, it describes a wire which is equal in cross-sectional area to the total of all the cross-sectional areas of the individual strands; the gaps between strands are not counted.
(Source - ibid.)
So, stranded 16 AWG wire is roughly 0.0533" in diameter and 10 AWG is roughly 0.1070" in diamter.
