Getting the ring size right is a must for any engagement ring. After all, you’ve invested a lot in selecting the perfect ring and planning the proposal, so naturally you’ll want the ring to fit right out of the box.

In this blog, we’ll dispel some common myths floating around on the Internet and provide some reliable tips on how to determine her ring size, including an international ring size chart, so you can get it right.

Before you read any further, here’s a quick note on the importance of determining the right ring size. In general, rings with pavé and channel settings cannot be resized easily. It also can be very difficult to resize eternity/anniversary rings (that is, those with diamonds around the entire band). Examples of other ring styles that cannot be easily resized are given below.

In this blog we cover:

DON’T use a piece of string or paper to measure ring size
DO ask a jeweler to measure ring size
Estimate ring size with a bar of soap
Determine ring size with paper and pencil
Ask a friend or family member about ring size
A few more tips about ring size
Determine ring size with a ring size chart

DON’T use a piece of string or paper to measure ring size

Some websites suggest wrapping a piece of string around the finger, marking the place where the ends overlap and then finding the corresponding size on a ring size chart. Other sites suggest using a strip of paper to determine ring size, again by wrapping the strip around the finger and then marking the paper with a pen or pencil where it overlaps. Both methods lead to inaccuracies: String can stretch and paper can be easily damaged. Humidity and temperature can cause paper to shrink and curl.

Also, when you measure ring size this way, you’re not taking into consideration the size the ring needs to be to slip over the finger joint or knuckle. For most people, the joint is larger than the rest of the finger. If you only measure where the ring sits on the finger, she might not be able to push it over the joint when the time comes to put it on for the first time. Plus, you lose the element of surprise with this method, and if it’s not a surprise, you should ask your jeweler for help. Considering the symbolic value and cost of an engagement ring, you’ll want to determine ring size using more accurate methods. Read on for some reliable ones.

An 18.70 ct emerald cut diamond engagement ring flanked with two trapezoid-shaped diamonds.

An 18.70 carat (ct) emerald cut diamond is the star of this engagement ring. Two trapezoid-shaped diamonds flank it. An accurate ring size is critical for such a large stone, to ensure that it fits snugly but comfortably. Photo: Robert Weldon/GIA. Courtesy: A private collector and Mona Lee Nesseth, Custom Estate Jewels

DO ask a jeweler to measure ring size

 The best way to get the right fit is to have your beloved visit the jeweler with you and have the jeweler determine her ring size. A jeweler will probably use a set of finger gauges, often called a ring sizer, which contains a series of metal bands in ½ size increments that slide onto the finger to measure it for the most secure fit and best comfort. Your jeweler will also know how to factor in temperature, humidity, altitude and even time of day, which can also affect finger size. This takes any uncertainty and guessing out of the process.

A set of finger gauges used to determine ring size.

A set of finger gauges is the most accurate way to determine her ring size. Photo: Eric Welch/GIA

If you want to keep the element of surprise, you can always “borrow” a ring from her jewelry box and take it to a jeweler yourself. Just make sure it’s a ring she often wears on a ring finger as opposed to one she wears on her middle finger, thumb or index finger, as these will not be the same size. In addition, for a person who is right-handed, the left ring finger is typically smaller than the right ring finger by about half a size and vice versa.  Let the jeweler know if the ring you’ve brought is usually worn on the right or left hand and which hand is dominant.

To measure an existing ring, the jeweler will typically use a ring mandrel – a tapered cylindrical tool – that is marked with ring sizes. As with a finger gauge set, it can measure in half as well as full sizes. If the band is unusually wide, take the measurement from the center.

If none of these options work for you, some online merchants offer plastic ring sizers. These can give a fairly accurate measurement of her ring size.

A ring mandrel used to determine ring size.

A ring mandrel is used to determine ring size for an existing ring. Photo: Eric Welch/GIA. Courtesy: K.R. Gems & Diamonds, International

Estimate ring size with a bar of soap

 Another way to secretly estimate ring size is by using soap. Press one of her favorite rings (one she wears on her ring finger) into a bar of soap until it creates an impression. Be sure to carefully wipe the ring clean of any residue so she doesn’t become suspicious of your plan. Bring the bar of soap to your jeweler, who can use the markings to determine her ring size. Remember, though, to tell the jeweler which hand she wears the ring on and whether it’s her dominant hand.

An engagement ring with a twisted band style.

It’s important to get her ring size right, especially if you select an engagement ring with a twisted band. This style is more difficult to resize. Courtesy:

Determine ring size with paper and pencil

 Borrow one of your beloved’s favorite rings (again, a ring she wears on her ring finger), preferably one with a plain and unadorned band. Get a pencil and trace the inside of the ring on a piece of paper. This is a good way to determine her ring size.

A 1.55 ct diamond halo engagement ring with bead-set melee.

A 1.55 ct diamond is cradled in a halo of bead-set melee. The tiny diamonds set into the thicker band may make this ring difficult and more expensive to resize. Courtesy:

Ask a friend or family member about ring size

Still having trouble? Ask her friends or family members if they know her ring size. Asking her mom or a friend to go shopping with you may also be helpful.

Rose gold Toi et Moi triple band engagement ring.

Rose gold, a sculptural quality and a nod to vintage Toi et Moi (“you and me”) rings are a few of the elements that make up this unusual – and beautiful – engagement ring. Because of the triple band this ring would require more work to resize. Courtesy: Laurence Bruyninckx – Antwerp

A few more tips about ring size

If you’re still nervous about determining her ring size, here are a few things you should know for extra assurance that the ring you’re getting will be the perfect fit:

  • Buy a larger ring: It is easier to remove metal from a ring that’s too big than add metal to a ring that’s too small.
  • Shank size matters: Rings with wide shanks usually need to be a bit larger, as they will fit more snugly. Bridal sets wider than 4 or 5 mm when the band and engagement ring are worn together require special consideration. Be sure to consult your jeweler about how best to handle this.
  • Beads: Small gold balls can be added to the inside of a ring that’s too big to make it fit tighter and keep it from turning on the finger. This is especially helpful for people with larger finger joints. Additionally, jewelers can install mechanical shanks for people suffering from arthritis.
  • Weather, altitude and time of day: Fingers shrink in the cold and swell in the heat. Consequently, not only can a measurement taken on a winter day differ from one taken mid-summer, but a measurement taken on a cool morning can also differ from one taken in the afternoon, as the temperature rises. Likewise, high and low humidity can cause a finger to swell or shrink. So can altitude – like flying and mountain climbing. Be mindful of this when you pick her ring size.
1.34 ct heart shaped diamond engagement ring accented with melee.

Not only will she fall for this 1.34 ct heart shaped diamond engagement ring accented with melee, but she’ll be even more surprised that you got her ring size right. Courtesy: Yael Designs

  • A snug fit: The ring should be snug on her finger, but not so tight as to cause discomfort. Make sure she can slide the ring over her knuckle, but it won’t fall off accidentally while she is working, playing or even just washing her hands.
A 2.00 carat (ct) emerald cut diamond engagement ring is framed by milgrain and another 0.75 carats of diamonds in the shank.

A 2.00 ct emerald cut diamond is framed by milgrain (tiny metal beads). Another 0.75 carats of diamonds sparkle in the shank. If the diamonds go all the way around, this would be a difficult ring to resize, so determining your loved one’s ring size before making the purchase is critical. Courtesy:

Determine ring size with a ring size chart

Different countries use different scales to measure ring size. We make sense of these differing standards in the international ring size chart below.

International Ring Size Chart

Inside Diameter Millimeters (mm) Inside Circumference  Millimeters (mm) U.S. and Canada U.K., Europe and Australia Switzerland Asia (Hong Kong, China, Singapore, Taiwan, Japan)
14.1 44.3 3 F 4 4
14.3 44.9 3.25 F.5 5.25 5
14.5 45.6 3.5 G
14.7 46.2 3.75 G.5 6.5 6
14.9 46.8 4 H 7
15.1 47.4 4.25 H.5 7.75
15.3 48.1 4.5 I 8
15.5 48.7 4.75 1.5 9
15.7 49.3 5 J 9
15.9 50.0 5.25 J.5 10
16.1 50.6 5.5 K 10
16.3 51.2 5.75 K.5 11.75
16.5 51.8 6 L 12.75 11
16.7 52.5 6.25 L.5 12
16.9 53.1 6.5 M 14 13
17.1 53.7 6.75 M.5
17.3 54.3 7 N 15.25 14
17.5 55.0 7.25 N.5
17.7 55.6 7.5 O 16.5 15
17.9 56.2 7.75 O.5
18.1 56.9 8 P 17.75 16
18.3 57.5 8.25 P.5
18.5 58.1 8.5 Q 17
18.8 59.1 8.75 Q.5 19
19 59.7 9 R 18
19.2 60.3 9.25 R.5 20.25
19.4 60.9 9.5 S 19
19.6 61.6 9.75 S.5 21.5
19.8 62.2 10 T 20
20 62.8 10.25 T.5 21
20.2 63.5 10.5 U 22.75 22
20.4 64.1 10.75 U.5
20.6 64.7 11 V 23
20.8 65.3 11.25 V.5 25
21 66.0 11.5 W 24
21.2 66.6 11.75 W.5
21.4 67.2 12 X 27.5 25
21.6 67.9 12.25 X.5
21.8 68.5 12.5 Y 28.75 26
22 69.1 12.75 Z
22.2 69.7 13 Z.5 27
22.4 70.4 13.25
22.6 71.0 13.5 Z1

Now that you’re armed with these tips on how to determine ring size, you’ll be ready to surprise your bride-to-be with a ring that fits perfectly on her finger. Our 12 Tips for Buying an Engagement Ring will also help you on your quest to find the perfect engagement ring and feel confident about your purchase.