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

If you’re wondering how to find out your partner’s engagement ring size without her knowing, you’re not alone. To help all you soon-to-be proposers, we spoke with jewelers large and small, online and brick and mortar, to collect 10+ ways to measure engagement ring size without ruining the surprise.

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Photos by Amy and Jordan

Use one of their other rings to get a size approximation

This is possibly the easiest and oldest trick in the book. If your partner’s out of town—or you know they absolutely won’t notice one of their rings missing—you can take a ring out of their jewelry box and do a few things with it:

1. Take it straight to the jeweler and they’ll measure the ring size it for you.

“On top of taking the ring discreetly, it’s important to know which finger and hand they wear the ring that you snagged on,” says Craig Rottenberg of Long’s Jeweler’s in Boston. “Why? A person’s dominant hand might be larger than their less dominant hand and each of their fingers will have a different ring size.. If you give this information to your jeweler, they can usually help you come up with an approximate size based on proportions they typically see.”

2. Order a ring sizer online.

For a hands-on approach, size it yourself. You can order a complimentary ring sizer on James Allen.

3. Use a pen and paper (or your finger) to document their ring size.

You can trace the inside of their ring on a piece of paper and then your jeweler can figure out the diameter of the ring from your sketch (Blue Nile also has a printable ring size guide if you’re planning to buy online)! But even better, here’s amazing advice from a jeweler:

“The most accurate way we’ve found is to take a ring your partner wears often while they’re not paying attention and put it on one of your own fingers,” says Alexis Padis of Padis Jewelry in San Francisco. “Then, take a pen and draw a line on your finger directly below where the ring is sitting. After that, head to your jeweler so they can use one of their ring sizers to find the best match based on where the line is on your finger. The biggest reason you want to get their ring size right is so that at the very least, it’ll slide on their finger at the time of the proposal—that’s why we recommend you draw the line on your finger right below the ring, versus above it. It’s better to slightly overestimate their size and it be too big, than slightly underestimate it and they’re not be able to wear it after you propose. It’s way easier to resize a ring that’s too big than too small.”

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Enlist the help of her friends to determine ring size

It’s probably easier than you think to have a friend sneak the ring size topic into conversation. Quite frankly, they also might already know the answer. Here are a few ways to enlist some of your partner’s friends to determine engagement ring size:

1. Choose a friend or two that already has an engagement ring.

At brunch (or something similar) have one of the friends bring up rings and then suggest they all swap and try each other’s on. When your ringless partner tries their friends’ on, they’ll be able to judge how big or small their ring was on them. They might even drop some hints as to what they want in this conversation, so remind the friends to keep their ears open for more than just engagement ring size details.

2. Have one of your partner’s friends ask them to go engagement ring shopping (for the friend, not your partner).

Unless said friend is also likely getting engaged soon, it would be random for a single person to suggest to your partner that they make a specific plan to try rings on. Instead, we suggest it’s a “coincidence” that they go to a jeweler. Perhaps they make plans to go to the mall and when they pass a jeweler there, the friend says, “Hey, I have a random idea…”

3. Have your partner’s best friend flat out ask them their ring size.

This is a bit of a best friend duty to make sure your BFFL gets the ring of their dreams. Why not have a friend, sibling or parent of your partner’s say, “At some point, you and I both know, Jim is going to need to know your ring size. I’m not saying it’s any time soon or not soon, but let’s figure it out in case he ever does come to me.”

Ask her for her ring size yourself

This is a similar concept to the one above. Most couples do talk about engagement at some point before it happens, so it’s completely appropriate to say you’d like to know what their ring size and favorite style is.

“If you’re at the stage where you know you want to marry your partner, chances are you’ve talked together about taking that next step,” says Oded Edelman of James Allen. The ring you choose, the timing of the proposal and the way you propose can still be a complete secret—no harm in asking directly for their ring size.”

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Pull a really stealth move and size their finger while they sleep

Hear us out: If you have a deep sleeper on your hands, this can be an awesome way to figure out your partner’s ring size. (It can also make for a hilarious story down the road.) While your partner is in Sleeping Beauty mode, take a simple string, fishing line, or piece of paper and wrap it around their finger on their left hand. It could take a couple nights to get it right, but you’re in the clear as long as they don’t wake up.

Get creative (like, actually do art)

Remember those drawings you used to do around Thanksgiving? The ones where you’d trace your hand and then embellish the heck out of it to make it look like a turkey? That same approach can be applied here.

“As hokey as this may sound, do an art project together—something that involves getting their hand in paint and then onto a piece of paper,” says Adrienne Fay of Borsheims Fine Jewelry and Gifts in Omaha, NE. “A jewelry associate is typically so skilled that they can work for an estimate from that on a ring size.”

Don’t stress—it can be resized

All of these tips said, don’t stress just know you can get it resized. Long’s Jewelers in Boston offers free initial resizing for your partner, and we suspect a lot of jewelers offer the same. The key is to getting it close (and as stated above, to err on the side of caution by making it bigger than smaller), and then perfecting it later.

If you need more advice, we have a good amount of proposal planning tools such as our engagement ring finder, an article on how to find her ring style, or our proposal idea generator. We also have a directory to help you book proposal photographers + other vendors. Good luck, guys.

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All photos provided by Amy and Jordan!

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