i need to know if uk aran is equivalant to a number 5 or 6 usa yarn would much appreciate it Gauge
Using size usa 7 needles, 9 stitches x 14 rows stocking stitch = 5 cm/ 2 inches
thank you

Neither. A 5 is bulky and a 6 is super bulky. It's more equivalent to the US worsted weight 4, espeically using a size 7 needle and that gauge.