You put your favourite ring on in the morning and it fits perfectly. By lunchtime it feels a little snug. Later that evening you take it off without thinking about it. Then, on another day, the same ring seems determined to spin around your finger every thirty seconds.
Has your ring somehow changed size overnight? Thankfully, probably not.
Your fingers aren't a fixed size
We tend to think of ring size as one exact measurement. You are a size N. Or Q. Or T½.
Nice and simple.
Except the human body doesn't work like that.
Our fingers naturally change size throughout the day. Temperature is one of the biggest culprits. When we're warm, our fingers can swell slightly. When we're cold, they can contract. This is why a ring that feels perfectly comfortable in winter might suddenly seem tighter on a hot summer afternoon.
Activity can make a difference too. So can the time of day and a number of other perfectly normal changes in the body. Even the shape of your finger matters, some people have a larger knuckle with a narrower section below it, meaning a ring needs to be large enough to comfortably pass over the knuckle without being so loose that it spins once it gets there. Others have fingers that taper more evenly.
Then the ring itself matters
A delicate 2mm band and a broad 8mm band in exactly the same nominal size can feel completely different.
Wider rings have more contact with the finger and will generally feel firmer. The shape of the inside of the band can also affect how a ring feels, as can wearing several rings together.
This is why guessing your ring size from another ring isn't always as straightforward as it sounds.
So when should you measure your finger?
Ideally, when your hands are at a comfortable, normal temperature — not immediately after coming in from the freezing cold and probably not after spending an hour gardening on a 35-degree day.
If you're unsure, take measurements at a few different times.
And for an important ring, particularly an engagement or wedding ring that you'll be wearing regularly, having your finger properly sized by a jeweller is always worthwhile.
A good ring fit isn't necessarily one that feels exactly the same every minute of every day.
