Floral wire comes in various gauges, the higher the gauge number the thinner the wire.
1 gauge, 7mm in diameter
3 gauge, 6mm in diameter
5 gauge, 4.5mm in diameter
7 gauge, 3.6mm in diameter
9 gauge, 2.9mm in diameter
12 gauge, 2.0mm in diameter
16 gauge, 1.3mm in diameter
20 gauge, 0.8mm in diameter
24 gauge, 0.5mm in diameter
2 gauge, 6.5mm in diameter
4 gauge, 5mm in diameter
6 gauge, 4mm in diameter
8 gauge, 3.2mm in diameter
10 gauge, 2.6mm in diameter
14 gauge, 1.6mm in diameter
18 gauge, 1.0mm in diameter
22 gauge, 0.6mm in diameter
26 gauge, 0.4mm in diameter