If you are going into a jewelry store to buy a ring, then the store assistant will have a ring size tool, which is simply a series of metal rings into which you can slip your finger in to find out the ring size that you need. However, if you are buying rings online and you don’t know what size your fingers are, how do you work out what ring size will fit you? Here is a handy guide on how to find your US ring size at home.

What time of day do you measure your ring size?

Your fingers change size through the course of the day because they can be affected by the temperature. If it’s very cold your ring size will be smaller than usual, and if it’s very hot, your ring size will be larger. In fact, your ring size can fluctuate by as much as half a size through the course of a day. The best time to measure your ring size is in the evening because that is when the temperature will be nearer to the average.

Which finger do you measure?

Always measure the actual finger that the ring that you are buying is for. You can’t measure the same finger on the opposite hand, because the fingers of your dominant hand are quite likely to be around half a size bigger than the fingers of your non-dominant hand.

What type of ring are you buying?

The types of the ring that you are buying can affect how you measure your ring size, as can the positioning of the ring on your finger. If you are buying a wide band ring, you might want to consider a ring size half a size bigger than your actual ring size to make wearing the ring more comfortable. You should also measure your ring size on the part of your finger that you are going to wear the ring.

How to measure your finger at home

To be able to work out your ring size you will need to measure the circumference or diameter of your finger. You can buy your own ring size tool if you like, but as most of us don’t buy rings all that often, that’s probably an unnecessary expense.

To measure your finger, simply take a piece of paper or a length of string and wrap it around your finger, making sure that it isn’t too tight. Then mark the point on the string or paper where it meets to form a circle, and then you can measure the length of the paper or string to find the circumference of your finger.

How to calculate your US ring size

Once you know the circumference of your finger, working out your ring size is very straightforward. Simply locate the circumference of your finger, in either millimeter of inches, on the chart that we have provided below, and then you will able to look up your US ring size.

Different countries use different ring sizes.

You need to be aware that if you buy a ring from an overseas website, you will have to look up the local ring sizes because different countries use different standards of ring sizes. The US ring sizes are only used in the US and Canada. The UK, Australia, and Ireland use a system of letters to denote ring size, India, Japan, and China use a different numbering system from the US, and other countries use ISO standard ring sizes. We have included the British, Japanese, and Swiss ring sizes in our ring size chart below.

How to find someone else’s ring size and keep it a surprise

If you are aiming to surprise someone with a ring, finding the right ring size for them is going to be a bit trickier. You could try to borrow a ring that the person already owns and take the ring size from the diameter of that, but you will need to make sure that it is a ring that the person wears on the same finger that they will wear the ring that you are buying them. Alternatively, you could ask someone who might know, like the person’s parents or friends.

If you are really can’t find out what another person’s ring size is then it might be useful to know that the average ring size for a man is 9 to 10 and the average ring size for a woman is 6 to 6.5. If you have no other way to finding out someone’s ring size and you have to make a guess, it is better to go to the upper end of your estimate so that at least the ring will fit on the person’s finger when you surprise them with your gift, even if the ring has to be made slightly smaller later on.