How to (discreetly) Find out Ring Size! Ring Size Chart

The Ring Calculator even makes it possible to do it secretly and at home: instructions and tips for correctly measuring with or without a ring plus a ring size table and conversion chart.

At a Glance

  • There are several ways to determine your partner’s ring size: (1) by using a string or dental floss to measure, (2) by using an existing well-fitting ring as basis, and (3) by using a ring size stencil.
  • If the ring is too tight or too wide, a professional can stretch out the metal or work on shrinking it with a machine. In case of a major difference, it is also possible to add or remove a piece of the ring band material.
  • There are various standard systems for ring sizes. In the US, ring circumferences are assigned a corresponding number. In the UK, instead of numbers, sizes are labeled with letters. In France, the ring diameter is subtracted by another 40 millimeters (formula: diameter – 40 = ring size).

If you want to purchase a ring as a gift or for your engagement, you have a tough task ahead! For how can you best determine ring size secretly without your partner suspecting? Ring templates are too obvious. The same goes for measuring the finger diameter. But if you can measure the inside diameter of a ring that fits, this Ring Size Calculator will let you convert it to such international sizes as those used by the English, American, and French.

Why is the right ring size important? Having to make a ring wider or narrower always contains risks. Even the most experienced jeweler can make a mistake. Therefore: if you are buying a ring for yourself or even a wedding ring, take your time and measure precisely. Templates are not at all necessary; the instructions below require only a string and a ruler.

Calculate ring size + a ring size table

Ring size charts + Calculating the ring size without the ring

So that you don’t go OUCH when putting the ring on, but instead get it to fit perfectly! Here, you will find the best methods for determining the correct ring size. Do you want to secretly find the right ring size to surprise your girlfriend or boyfriend? We have the right guide for that too. And, of course, the 10 best tips for buying a ring! 

The 10 best tips for taking measurements

  1. Measure the ring finger.
  2. Measure in the evening or after light sporting activities.
  3. Measure on days when you are hydrated enough.
  4. Do not measure when you are feeling cold.
  5. Be careful when taking measurements.
  6. For gifts, choose a ring that is slightly bigger rather than going for the smaller size first.
  7. Observe the shape and width of the ring: These features can also influence the final result.
  8. For finger measurements: Measure often and on different days.
  9. Let a jeweler advise you and if in doubt, get them to determine the ring size too.
  10. If the determined ring size does not fit, you can often just change the ring.

Christmas, birthday, engagement or, of course, the wedding – all the reasons for buying a ring are quite diverse. But one thing the ring should always be is: A good fit!

Ring Size Chart

Circ. (CM)Diameter (CM)SizeUKUSFR
40,512,940,5-1 -0,5
43,313,843E2 -3
45,914,645,5G3 -5,5
47,11547H4 7
48,415,448I4 -8
50,916,250,5K5 -10,5
53,41753,5M6 -13,5
5517,554,5N7 14,5
55,917,856O7 -16
58,118,558,5Q8 -18,5
61,319,561S9 -21
63,820,363,5U10 -23,5
662166W11 -26
67,521,567,5X12 27,5
69,12269Y12 -29

Since the human body is not absolutely symmetrical, the fingers of the left and right hand often differ. Therefore, you should already know beforehand, which exact finger the ring is to be worn on later. For example, engagement rings are worn on the left hand, while the wedding ring is normally found on the right ring finger.

How Do You Find Out Your Partner’s Ring Size Without Them Knowing?

To determine the ring size without the ring, you will have to resort to a few little tricks. The measurement method using a string or dental floss is popular. Find some string that is at least the length of a palm. Tie it around the root of the selected finger and make a knot around it. The string should be as close to the finger as the ring will be. Not too loose, but not too tight either. The knotted loop must also be able to be pushed over the joints of the finger. Cut the loop close to the knot and use a ruler to measure the length of the loop in millimeters. Depending on the jeweler or dealer, you have to change the length to a different measurement.

This is how you determine the ring size with the ring

If you already have a well-fitting ring, the ring size is easier to determine. Cut a small strip of paper. Roll it in length and place it in the ring opening. The paper strip should cover the entire inner circumference. Use a sharp pencil to mark the point where the strip overlaps. Now remove the paper strip to measure the length of the strip to the mark with a ruler.

Alternatively, the ring diameter can be used to determine the ring size. Using a ruler, measure the widest part of the ring from one inner edge to the opposite inner edge. Now you only have to determine the circumference with a small calculation task. Multiply the diameter in millimeters with Pi 3.14 (diameter * 3.14 = circumference), or by using our ring size calculator.


What is a ring size stencil?

A ring size stencil simplifies ring size measurements. The stencil is a thin sheet of plastic, cardboard or paper, which has holes of different sizes. Each hole is marked with the appropriate ring size. To determine the ring size, all you have to do is try the stencils with your fingers.

Can rings be tightened or made wider?

Despite careful measurements, the finished ring may be too tight or too wide. It can then be changed. To this end, the professional will use two methods: If the ring is too tight, it will be stretched. In case of a major difference, the ring will be opened and additional material will be added. In the case of making the ring tighter, it can be worked with a machine. It is also possible to remove a piece of the material.

Whether or not the procedures are applicable to your ring depends on whether and how well the ring was filled with stones and the material from which it was made. Gold and platinum rings are usually easy to change, but stainless steel rings represent a greater challenge. Gemstones can lose their hold with the changes made, which is why they may have to be re-inserted. Engravings on the ring sometimes have to be completely recreated. 

What ring sizes are there?

There are five standard systems for ring sizes. The Viennese Association for Measurement is widespread in Germany. The size corresponds to the circumference of the inner side of the ring in millimeters. Alternatively, the ring diameter can be specified here. The French measure is a bit more complicated because in this case, the ring diameter is subtracted by another 40 millimeters (formula: diameter – 40 = ring size). For the English measurement, a letter is assigned to each circumference of the ring. The appropriate size can be determined using charts. It is similar to the American system of measurement, except that they assign numbers instead of letters.

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