Learn How to Find Her Ring Size

If she wears a ring on her left-hand ring finger, see if you can borrow it without her noticing. Depending how much time you’ll have with the ring before she realizes it has been borrowed, here are a few tactics to consider:

• If you have a few hours — Take the ring to a local jeweler to size it professionally. While this takes more time, a jeweler is generally the best place to measure for ring sizes because it’s the most accurate. 
• For a quick and accurate sizing in less time, invest in a ring mandrel and measure the ring yourself. Slide the ring down the mandrel. The line where the ring stops indicates its size. 
• If you have a several minutes — Use the ring sizing chart. Be sure to print it ahead of time and use a ruler to double check it’s precisely to scale. Move the ring from circle to circle until you find the best match for the ring’s inner diameter. If the ring lands between two sizes, always choose the larger one. 
• Trace it. Carefully trace the inside and outside of the ring on a piece of paper. Repeat several times for added accuracy. Take the paper to a jeweler for a size estimate. 
• In a pinch — Try it on yourself. See if the ring fits one of your fingers comfortably. If it does, you can measure that finger later, on your own time.

Pretend that you’d like to buy a ring for someone else, whether it’s your sister, 

grandmother, mom or aunt, and ask for her help. Not only could you discover her ring size this way, but you could learn a lot about her design preferences and style. Here are a few tactics to try out:

• ASK HER IF SHE KNOWS HER OWN RING SIZE — CASUALLY. As you browse for rings, say something like, “I don’t know what ring size my mom wears. Do you know yours? Maybe I can use you as a reference.” Be sure this feels like a natural part of the conversation, otherwise you could raise suspicion. 
• TAKE HER SHOPPING. Ask her to try on rings as part of your gift shopping experience. Pay attention to which size fits her best. If needed, take a solo trip to the store ahead of time to familiarize yourself with where and how sizes are listed. 
• ASK HER OPINION. If visiting a store together is not possible, try purchasing an inexpensive ring you think would fit her. Casually ask her to try it on to make sure it “looks good” before you gift it to your mom, sister, aunt, etc. Pay close attention to the fit.

If there’s a close friend or family member you know you can trust, ask them to help you learn her ring size. Just make sure it’s someone you know can keep a secret. Here are some ideas on involving someone else:

• Do they already know her ring size? Perhaps her mom or best friend recently purchased a ring for her as a gift. In this case, they may already know her size. 
• Can they go jewelry shopping together? Whether at an artisan market, the mall or a jewelry store, they could browse for rings while also noting her size. 
• Can they simply ask her? If the question fits naturally into a conversation, they can ask for her ring size directly without giving away your intention.

Another way to measure ring sizes is to print out your own ring sizer. Here’s how:

1. Print the image. Make sure the scaling of the page is set to 100%. 
2. Measure the 3½ inches with a ruler to ensure the printout is precisely to scale. 
3. Trim the paper to match the outline and cut a slit as indicated by the vertical line. 
4. Insert the pointy tip of the paper through the slit. 
5. Place the paper around her finger and gently tug until you have a secure, comfortable fit. 
6. The number line that meets the slit indicates the ring size. 
7. Consider repeating steps 4-6 a few times to ensure accuracy.

There’s a margin of error with almost all of these methods, so here are a few other considerations to take into account:

• If you’re between two sizes, always go with the larger one. It’s generally easier to size a ring down if needed. 
• Wider rings typically have a tighter fit and may require a slightly larger size to fit comfortably. 
• Avoid measuring her ring size first thing in the morning or on extremely hot days when her fingers could be more swollen than usual.