Size of the ring (finger measurement): - UK N (17.10mm dia. 53.72mm circ) UK O (17.50mm dia. 54.98mm circ) UK P (17.90mm dia. 56.23mm circ) UK Q (18.30mm dia. 57.49mm circ) UK R (18.70mm dia. 58.75mm circ) UK S (19.10mm dia. 60.00mm circ) UK T (19.50mm dia. 61.26mm circ) UK U (19.90mm dia. 62.52mm circ) UK V (20.30mm dia. 63.77mm circ) UK W (20.70mm dia. 65.03mm circ) UK X (21.10mm dia. 66.29mm circ) UK Y (21.50mm dia. 67.54mm circ) UK Z (21.90mm dia. 68.80mm circ) UK Z+1 (22.30mm dia. 70.06mm circ) UK Z+2 (22.70mm dia. 71.31mm circ) UK Z+3 (23.10mm dia. 72.57mm circ) UK Z+4 (23.50mm dia. 73.83mm circ)