How To Accurately Measure Ring Size

Measuring Your Ring Size

Congratulations, you've found your perfect ring. Now, determining your accurate ring size is a critical next step. Most of our rings cannot be resized because they contain a unique material inlay, overlay or sleeve.And, rings fit very differently depending on width and fit (comfort vs. standard).

Have no fear, follow the 4 steps below to find your ring size easily and accurately.  

STEP 1: GET AN ESTIMATED RING SIZE

OPTION 1 (RECOMMENDED)

VISIT YOUR LOCAL JEWELER AND GET SIZED

Visit at least two local jewelers and ask them to measure your finger in a COMFORT FIT (unless stated otherwise on your desired ring design), ideally using a caliper or micrometer. Measuring with a mandrel may result in less accurate sizing because not all mandrels are manufactured exactly the same. We strongly suggest you visit more than one jeweler; the goal is to find multiple jewelers who agree on your estimated size and then proceed to STEP 2.

how to measure a ring with a mandrel

RULE OF THUMB: The size is read where the inner edge makes contact with the ring size mandrel.

Accurate sizing measurement is dependent on the ring fit (STANDARD vs COMFORT).


COMFORT FIT

Measured from the middle; the inside is rounded and bows out in the center.

STANDARD FIT

Measured from the bottom, leading edge; the inside is flat and uniform.


A WORD OF CAUTION REGARDING RING MANDRELS

It's important to note that not all mandrels are created the same. They are not standardized and measurements can vary dependent on the mandrel manufacturer. Sometimes there are even discrepancies in size readings among mandrels created by the same manufacturer. This video illustrates this phenomenon.

OPTION 2

ORDER A FREE RING SIZING KIT

Order your ring along with our free sizing kit, which is offered as a convenient alternative to visiting a local jeweler to get an estimated size. Sizing kits are shipped within 1-2 business days. The kit is most accurate for rings with a width of 4mm. That said, if your desired ring is wider than 4mm, we DO NOT recommend having us craft your ring based on the best-fitting size from this kit. Please proceed to STEP 2!

OPTION 3

MEASURE AN EXISTING RING

If you're fortunate to have an existing ring in the same fit (comfort, standard, etc.) you are planning to order, you can bring this ring to a jeweler to use a CALIPER to measure the inside diameter of it in MILLIMETERS. This measurement can be used along with our Ring Sizing Conversion Chart (located at the very bottom of the page) to determine U.S. ring size. Although this is considered a more accurate way to obtain estimated size, we still strongly suggest proceeding to STEP 2.

how to measure a ring with a caliper

A ring’s size can be determined by using a caliper, but it requires some math and is most accurate on plain bands. The following example illustrates how properly measuring both a comfort fit and standard fit ring will result in the same, accurate size.

STEP 1: MEASURE THE OUTSIDE DIAMETER (OD)

Take three separate measurements and record the average.

The three OD measurements (23.91+23.93+23.92 ) divided by 3 = average 23.92 mm

STEP 2: MEASURE THE RING THICKNESS (TH)

Take three different measurements of the ring and record the average. The process is the same for both COMFORT FIT (rounded on the inside) and STANDARD FIT (flat on the inside). However, because the sleeve shapes are different, the measurements will be different (illustrated below).

COMFORT FIT THICKNESS

The three COMFORT FIT measurements (2.81+2.82+2.83 ) divided by 3 = average 2.82 mm


STANDARD FIT THICKNESS

The three STANDARD FIT measurements (2.77+2.78+2.76) divided by 3 = average 2.77 mm

STEP 3: CALCULATE THE INSIDE DIAMETER (ID)

Use the averages obtained in Steps 1 and 2 above to run the following formula:

Outside Diameter (OD) - Thickness (TH) - Thickness (TH ) = Inner Diameter (ID)

COMFORT FIT: 23.92 - 2.82 - 2.82 = 18.28 mm ID

STANDARD FIT: 23.92 - 2.77 - 2.77 = 18.38 mm ID

STEP 4: REFER TO THE RING SIZING CONVERSION CHART

Our Ring Sizing Conversion Chart allows you to convert your ring's ID measurement into U.S., French, German and other sizes.

With our sample, we learn that a ring with an inner diameter 18.28-18.38 mm is equal U.S. size 8.25!

STEP 2: ORDER A CUSTOM SIZER IN YOUR ESTIMATED SIZE

Order your ring, if you haven't done so already, along with a custom ring sizer in your estimated size(s) and gain total peace of mind! Per our policy, if you order a custom sizer and your ring does not fit perfectly, we will re-make it for no cost to you.  

Our custom sizers cost just $10 each and are THE most accurate way to determine your size because we create them in your estimated size, width and fit of your desired ring. Many customers also order the next smaller and larger sizes to allow for 100% accuracy and comfort. For example, if your estimated size is 9, consider also ordering custom sizers in sizes 8.75 and 9.25.

Most custom sizers are made-to-order and ship within 1-2 weeks. If we have your desired width/size in stock, it will ship within 3-5 days.

STEP 3: WEAR YOUR CUSTOM SIZER FOR 48 HOURS

Your custom sizer(s) will arrive with instructions, but it's pretty simple; wear the custom sizer for 48 consecutive hours to determine if the ring is comfortable. If you ordered multiple sizes, wear each of them separately for 48 hours and determine what size is the most comfortable.

How should your ring fit?

In reality, "fit" is subjective, but a ring that fits is a ring you forget that you're wearing and is secure (not too loose such that it will easily fall off). Here are some useful guidelines for determining a proper fitting ring.

  • For many, a good fit means comfortable most of the time. Your fingers change in size very slightly over time, which means that there is no "perfect" ring size. There are inevitably going to be days when your ring feels tight and days it feels looser. Your fingers fluctuate in size during the day due to temperature, diet, activities, and other factors. The time of the year also contributes to ring fit. You may notice it feels tighter in warmer months and looser during cold weather. Keep that in mind while you're wearing your custom sizer.
  • A ring should fit easily over your knuckle, you should be able to get it on without struggle and then have a slight pull at the knuckle when removing it. You may need to twist the ring 1-2 times to get it off. Proper sizing is more of a personal preference than a perfect science.
  • Finger shape plays a large role in determining the right fit of a ring. Some fingers are largest at the base and gradually taper without a prominent knuckle. On this type of finger, the ring should fit snugly at the base without causing bulges or a permanent indent. You should be able to push the ring up from the underside of your finger and see a small space between the ring and your finger.
  • Sizing fingers that are largest at the knuckle can be trickier. The key is to size the ring so it fits comfortably over the knuckle without being too large for the base of the finger. If there is a large size difference between the knuckle and base of the finger, the ring will spin and turn on the hand– especially engagement rings that tend to be top heavy. For some, this is welcomed because they like to fidget and spin the ring. For those that prefer it to be more static, a fix is to add sizing beads to the inside of the ring. They prevent some of the spinning while still maintaining a comfortable fit over the knuckle.

STEP 4: TELL US YOUR SIZE OR ORDER MORE SIZERS

If you're completely confident that you've found your personal "perfect" fit, contact us right away and tell us what it is. Your ring does not go into our production queue until we have a confirmed size.

If none of your custom sizers fit to your liking, order one or two more, but keep in mind, this will add more time before we can get started on your ring.


INTERNATIONAL RING SIZING CONVERSION CHART

US Size Inner Diameter (mm) Circumference (mm) British French German Japanese Swiss
2.000 13.19 41.43 D   13.50 2 1.75
2.125 13.29 41.76          
2.250 13.39 42.08 D 1/2 42     2.25
2.375 13.50 42.41          
2.500 13.60 42.73 E   13.75 3 3.00
2.625 13.71 43.06   43      
2.750 13.81 43.38 E 1/2       3.5
2.875 13.91 43.71          
3.000 14.02 44.03 F 44 14 4 4.25
3.125 14.12 44.36          
3.250 14.22 44.68 F 1/2     5 4.75
3.375 14.33 45.01   45      
3.500 14.43 45.34 G   14.50   5.5
3.625 14.53 45.66          
3.750 14.64 45.99 G 1/2 46   6 6.00
3.875 14.74 46.31          
4.000 14.85 46.64 H   15 7 6.75
4.125 14.95 46.96   47      
4.250 15.05 47.29 H 1/2       7.50
4.375 15.16 47.61          
4.500 15.26 47.94 I 48 15.25 8 8
4.625 15.36 48.26     15.50    
4.750 15.47 48.59 J       8.75
4.875 15.57 48.92   49      
5.000 15.67 49.24 J 1/2   15.75 9 9.25
5.125 15.78 49.57          
5.250 15.88 49.89 K 50     10
5.375 15.98 50.22          
5.500 16.09 50.54 K 1/2   16 10  
5.625 16.19 50.87   51      
5.750 16.30 51.19 L       11.25
5.875 16.40 51.52          
6.000 16.50 51.85 L 1/2 52 16.50 11 11.75
6.125 16.61 52.17          
6.250 16.71 52.50 M     12 12.5
6.375 16.81 52.82   53      
6.500 16.92 53.15 M 1/2   17 13 13.25
6.625 17.02 53.47          
6.750 17.12 53.80 N 54     13.75
6.875 17.23 54.12          
7.000 17.33 54.45 N 1/2   17.25 14 14.50
7.125 17.44 54.77   55      
7.250 17.54 55.10 O       15
7.375 17.64 55.43          
7.500 17.75 55.75 O 1/2 56 17.75 15 15.75
7.625 17.85 56.08          
7.750 17.95 56.40 P       16.25
7.875 18.06 56.73   57      
8.000 18.16 57.05 P 1/2   18 16 17.00
8.125 18.26 57.38          
8.250 18.37 57.70 Q 58     17.5
8.375 18.47 58.03          
8.500 18.57 58.35 Q 1/2   18.50 17 18.25
8.625 18.68 58.68   59      
8.750 18.78 59.01 R       19
8.875 18.89 59.33          
9.000 18.99 59.66 R 1/2   19 18 19.5
9.125 19.09 59.98   60      
9.250 19.20 60.31 S       20.25
9.375 19.30 60.63          
9.500 19.40 60.96 S 1/2 61 19.50 19 20.75
9.625 19.51 61.28          
9.750 19.61 61.61 T       21.50
9.875 19.71 61.93   62      
10.000 19.82 62.26 T 1/2   20 20 22
10.125 19.92 62.59          
10.250 20.03 62.91 U 63   21 22.75
10.375 20.13 63.24          
10.500 20.23 63.56 U 1/2   20.25 22 23.25
10.625 20.34 63.89   64      
10.750 20.44 64.21 V       24
10.875 20.54 64.54          
11.000 20.65 64.86 V 1/2 65 20.75 23 24.75
11.125 20.75 65.19          
11.250 20.85 65.51 W       25.25
11.375 20.96 65.84   66      
11.500 21.06 66.17 W 1/2   21 24 26
11.625 21.16 66.49          
11.750 21.27 66.82 X 67     26.5
11.875 21.37 67.14          
12.000 21.48 67.47 X 1/2   21.25 25 27.25
12.125 21.58 67.79   68      
12.250 21.68 68.12 Y       27.75
12.375 21.79 68.44          
12.500 21.89 68.77 Z 69 21.75 26 28.50
12.625 21.99 69.09          
12.750 22.10 69.42 Z 1/2       29
12.875 22.20 69.75          
13.000 22.30 70.07     22 27 29.75
13.125 22.41 70.40          
13.250 22.51 70.72 Z1       30.5
13.375 22.62 71.05          
13.500 22.72 71.37         31
13.625 22.82 71.70          
13.750 22.93 72.02 Z2       31.75
13.875 23.03 72.35          
14.000 23.13 72.68 Z3       32.25
14.125 23.24 73.00          
14.250 23.34 73.33         33
14.375 23.44 73.65          
14.500 23.55 73.98 Z4       33.5
14.625 23.65 74.30          
14.750 23.75 74.63         34.25
14.875 23.86 74.95          
15.000 23.96 75.28         34.75
15.125 24.07 75.60          
15.250 24.17 75.93         35.5
15.375 24.27 76.26          
15.500 24.38 76.58         36.25
15.625 24.48 76.91          
15.750 24.58 77.23         36.75
15.875 24.69 77.56          
16.000 24.79 77.88         37.5
16.125 24.89 78.21          
16.250 25.00 78.53          
16.375 25.10 78.86          
16.500 25.21 79.18          
16.625 25.31 79.51          
16.750 25.41 79.84          
16.875 25.52 80.16          
17.000 25.62 80.49          
17.125 25.72 80.81          
17.250 25.83 81.14          
17.375 25.93 81.46          
17.500 26.03 81.79          
17.625 26.14 82.11          
17.750 26.24 82.44          
17.875 26.34 82.76          
18.000 26.45 83.09          
18.125 26.55 83.42          
18.250 26.66 83.74          
18.375 26.76 84.07          
18.500 26.86 84.39          
18.625 26.97 84.72          
18.750 27.07 85.04          
18.875 27.17 85.37          
19.000 27.28 85.69          
19.125 27.38 86.02          
19.250 27.48 86.34          
19.375 27.59 86.67          
19.500 27.69 87.00          
19.625 27.80 87.32          
19.750 27.90 87.65          
19.875 28.00 87.97          
20.000 28.11 88.30