Ring Sizing: What Actually Changes With Temperature

Finger size fluctuates with temperature, hydration and time of day by up to half a ring size, which is enough to matter when you're ordering online.

The most reliable measurement window is late afternoon, at normal room temperature, after a normal amount of water intake — not first thing in the morning or after exercise.

If you're between sizes, we generally recommend sizing up rather than down: a slightly loose ring is a cheaper, faster fix than a re-cast.

Editorial disclosure: this guide reflects our independent research and is not sponsored by any retailer named in it.