How to Find a Person’s Ring Size without Them Knowing

Last updated on

Our product recommendations are made independently, but we may earn affiliate commissions if you use a link on this page.

The feeling you get when you know you have found “the one” is indescribable as is the realization that you want to spend the rest of your life with them. Thoughts naturally may turn to marriage or some other form of commitment ceremony which often may involve physical symbols of the union such as rings.

Engagement rings are a very common way to express this desire to join together with the person you love and proposing can often include a surprise aspect. As a result if you plan to get an engagement ring one of the first things you need to know is the correct size of your beloved's ring finger.

In this article we are going to take a look at the best and often sneakiest ways to find out a person's ring size. This is so that you can surprise them with a token of your love for them and ask them to join you in making a lifelong commitment to each other.

How Are Ring Sizes Determined?

Traditionally rings are worn around the thickest part of the finger which ensures they are more likely to stay on. It is important to know the size of this part of a person's finger to ensure that the ring is not too tight nor is it too loose.

Ring sizing is dependent on the circumference (Circum) of the thickest part of the finger as measured in millimeters. This measurement is then converted from millimeters into standard ring sizes. So for example a measurement of 50 millimeters around the thickest part of the finger translates to a US/Canada/Mexico ring size of 5.25.

Interestingly this conversion is not the same for all countries so certain places will work with different scales. For example if you were to find a jeweler in Ireland because your partner has Irish heritage and you want to surprise them with something made in their ancestral home you will need to convert the measurement to match Ireland's sizing system.

If you live in the US and choose to order an engagement ring from Ireland and your partner's ring finger circumference is 50 mm this would convert to ring size K. It is very important to understand these regional differences to avoid confusion and purchasing a ring of the wrong size.

The table below lists ring circumference measurements and their comparative ring sizes based on location:

Ring Sizing Tips:

Our hands may look the same size but in truth they are not. In fact our dominant hand (the one we tend to write with) is usually slightly larger. This is why it is important to get the measurement for the correct finger on the correct hand.

The wider the band of a ring the tighter it will likely fit on the hand. This means if you are basing your measurement on another ring that belongs to the person it should have a roughly similar width with regards the band as the ring you intend to buy.

Finger width can actually vary based on body temperature so be aware that they can actually shrink or expand as a result of temperature.

You may have experienced fingers feeling puffy or swollen at times this is because the thickness of our fingers can vary depending on the time of the day. The best time to get an accurate reading of finger size is near the end of the day.

Some people may have issues with swollen knuckles or just naturally more prominent finger joints. If the knuckle tends toward being bigger you should get two measurements, one of the base of the finger and one of the knuckle. This will allow you to choose a size between these two measurements which should fit better

How Do You Measure Ring Sizes?

Some people are daunted by the concept of measuring for rings as it may seem a little complicated. The truth is that it really is not that difficult to do at all as long as you are patient. This is something that can be done easily at home with a tape measure. Pieces of string or even a length of dental floss.

Obviously if you are trying to find someone else's ring size that is a little tricker especially if you can’t just ask them outright. It may take some covert activity to get the measurement but in theory the actual measurement is simple.

Using a Tape Measure:

The easiest method to measure a finger's circumference is using a flexible tape measure so not one of those rigid retractable ones. You will want something that may be used for crafts such as crochet. These will easily wrap around a finger to give an accurate measurement.

These tapes usually come with inches written on one side of the tape and metric measurement units in the form of centimeters and millimeters on the other. It is millimeters that you are going to need because inches and centimeters are not refined enough to get an accurate reading.

You simply wrap the tape measure around the area of the finger which you need the circumference measurement from with the millimeter measurement side facing out. Where the tape measure meets itself again will dictate how many millimeters in circumference the finger is.

Using String or Dental Floss:

Sometimes you have to improvise a little especially if you do not have a flexible tape measure handy which of course not everyone does. You can achieve the same measurement results however with a piece of string or dental floss. The only difference being that you will add a step to the process.

This is a simple method whereby you wrap the string or dental floss around the thickest part of the finger firmly but not pull tight. You will then either mark or cut the string at the point that it loops round and meets itself again. This will allow you at a later time to compare the length of the string or dental floss to a tape measure.

You Can Use a Ring Sizing Tool

Rings are a common thing so it is not in the least bit surprising that there is an actual ring sizing tool. Jewelers use these to measure customers for rings and the average person can also buy one online relatively cheaply. If you want a free tool then you can print and cut one out from an online template.

There are a few different types including ones that are essentially tape measures but with a twist and ones that literally have a series of sized metal loops which can be used to test sizes. The metal loop tool however may not be very subtle as it may tend to jingle a little bit.

Whichever sizing tool you choose it will likely come with instructions. If you choose the print out option be aware that they are a little more flimsy and tend to tear. As a result you may want to print out more than one just in case the first one rips while measuring.

Is There an Ideal Time of Day to Measure?

This is a very good question because some of us may not be aware that our hands, including obviously our fingers, may swell throughout the day. Those who wear rings regularly may well know that at certain times or in particular conditions the rings will feel tighter and perhaps not move as freely.

So because fingers may swell or shrink throughout the day it is a good idea to try and get multiple measurements in order to get an average. At the very least try and get a measurement early in the day and later in the evening.

Ideally try and get a few measurements over the course of a few days. This obviously ups the difficulty of the covert measurement for a surprise ring but it is important to get a ring that fits comfortably and that will not fall off the hand.

How Can You Get a Ring Size Without the Person Knowing?

We now come to the tricky part: how on earth do you get an accurate ring size for someone without letting them know you need it? I mean honestly simply asking someone their ring size is a little too obvious and they would have to be a little clueless to not suspect certain intentions when asking this question.

Measure Another Ring

This would be the ideal scenario in terms of a convert ring size finding mission as it does not directly require the presence of the person. If they have a ring that they already wear on the finger in question or do so occasionally you can try getting a measurement from that.

This is going to require a little bit of math so bare with us while we explain. You will not be able to get a circumference measurement from the inside of a ring. This is just too tricky, it's not going to work like that. What you can do is measure the diameter of the inside of the ring.

You will measure the distance between the inside edge of one side of the ring across to the other inside edge. This will give you the ring's diameter and you now have all you need for a simple equation. Using the below formula you can determine the circumference of the ring,

Circumference = π x Diameter (π = 3.14159)

So as an example if the diameter is 16 millimeters this would be (16 x 3.14159 = 50.26). This would indicate a ring size between 5.25 and 5.5 in the US sizing guide. You will always want to go for the bigger size in order to avoid the ring being too tight or not fitting on the finger.

The obvious drawback of this method is that things like engagement rings are traditionally worn on a specific finger so most people will not just wear a ring on that finger unless they are engaged. Potentially there may not be a ring to measure.

It is important to remember that even though the person may have a ring on the same finger on the opposite hand they may not have the same size. It may be a close match but it could equally be much larger or smaller than its counterpart on the other hand.

Use a Piece of String

This method is going to take real stealth and if you get caught you might have a little explaining to do. This may seem a little creepy but come on we have romantic intentions here so it's surely forgivable. If your partner is a heavy sleeper try and wrap a piece of string around their ring finger while they sleep,

As mentioned earlier you will need to mark or cut this piece of string although in this situation marking it may be the preferred method. It may be hard to explain what you are doing in bed with scissors if they happen to wake up.

What if There Is No Way to Get a Measurement Secretly?

Sometimes you will just find it impossible to get the person's ring size secretly but this does not mean that the option for a surprise proposal has gone out of the window. The simple answer is you will have to purchase the ring without knowing the exact size.

Do not panic, this is not a terrible thing. Jewelers resize rings all the time and often you may even get a free resizing included in your purchase for just such an eventuality. You will have to try and make a reasonable guess regarding the ring size however.

Earlier in this article we included an in depth table of ring sizes around the world and we outlined some common size ranges for both male and female hands. Refer back to this table to give you some idea of what kind of size you may need.

In an ideal world you might even get the size perfect on the first try and there will be no need to have the ring altered. If the ring needs to be resized however there is no shame in this especially if you nail the secret proposal. They will not be thinking about something as mundane as having the ring altered.

Is Ring Resizing Expensive?

If you were not able to get the correct size and you need a resizing then you may have to pay a little bit of money. Perhaps you couldn’t get the finger measured secretly or you were a little off in your technique, don’t worry it's not the end of the world.

Sometimes as part of the ring purchase you may be offered one free resizing which obviously is a win win situation. Even if you have to pay for the resizing it is not generally too expensive. It will depend on the ring of course but it usually will not cost more than $100.

What Do Jewelers Do When Resizing?

Resizing is a simple process for a jeweler; they usually make a small cut at the base of the ring and will either remove or add ring material in order to either decrease or increase the rings circumference. This obviously impacts the price as if they have to add more gold or silver to the band there will be a materials cost.

Can You Resize All Rings?

This is an important point to remember when it comes to rings, some materials are just too difficult to work with when it comes to ring resizing. As a result if the ring has alternate metals like Tungsten or is especially ornate the jeweler may not be able to resize it.

At the point of purchase if the jeweler does not expressly tell you that a ring can’t be resized ask the question yourself. This is an important purchase and even if the size is perfect now years down the line the ring may need to be resized due to changes in the person's hand size.

Make sure you get a ring that can be resized if needed just in case. This is an important piece of jewelry that the person will likely want to wear throughout their lives.

Final Thoughts

Getting the size correct when buying a ring for engagements or other commitment purposes is important and ideally if you can get it right the first time that will add to the perfection of the moment. It can be hard to get a person's ring size without involving them in the process but if it is intended as a surprise you sometimes need to be a little sneaky.

Reference Diamond Size Chart

If you use any of the definitions, information, or data presented on Diamond Size Chart, please copy the link or reference below to properly credit us as the reference source. Thank you!