As emotional an affair as it is to propose marriage to the person you love most, it can also involve an incredible amount of planning and logistics. Besides making sure that the both of you are ready for a lifetime commitment, there’s also the business of preparing the ring, planning out the proposal, coordinating with your partner’s family, and all the other little details that must be attended to to make your proposal magical.

The first, of course, is making sure you have the perfect ring—both in style and in size. The last thing you need is for your partner to not even be able to slide on their engagement ring and show off the fruits of your labor and affection. To help you avoid a ring-related faux pas, we’ve come up with a few methods (both sneaky and not) that you could use to find your partner’s ring size.

1. Use one of the rings they already own

If your partner wears rings often anyway, you’re in luck. Pay attention to the rings they wear on their left ring finger—remember, ring sizes vary from finger to finger and from hand to hand, so always use the left ring finger for reference!—and try to sneak off with one of them for a while.

If you don’t have much time with it, you can use it with the TrueFacet Ring Size Guide or trace the inner and outer sides of the ring and bring that to a jeweler. If their ring is smaller than one of your fingers, another method you can try is to slip it on your finger and draw a line on your finger directly under the point where the ring gets tight. A jeweler can use that line to figure out their ring size.

Remember, the ring also has to fit over the knuckles of your partner’s finger, so it’s better if the ring is a little loose rather than too tight. It can easily be resized after the proposal, if necessary, and loose rings are easier to resize than tight ones. Ideally, though, if you can borrow their ring for longer, take it directly to a jeweler and have them tell you the size.

2. Make arts and crafts

Artsy couples, take note—your next joint project may be the key to finding out your partner’s ring size. Make a project using painted handprints—or, even better, a mold of their left hand, if you can swing it—and bring the project to a skilled jeweler. Using the width of the ring finger on the handprint, the jeweler may be able to extrapolate an estimate of your partner’s ring size. As corny as it may sound, it could be a fun project to do together and be a creative way to figure out your future spouse’s ring size. Bonus points if you can come up with a project that would actually be fit to be displayed in an adult’s apartment. We’re partial to this cute handprint cactus.

3. Compare their size to yours

This is probably the least precise method of learning your significant other’s ring size, but it’s also the most convenient for you. All you have to do is look at your hand and theirs and gauge how much bigger or smaller their ring finger is compared to yours. Is wider than yours? Is their finger more slender than yours is? If you can gauge and quantify all of this simply by looking, you have a great shot at estimating their correct ring size.

4. Have them try on other rings to gauge their size

Bring your partner on a field trip to your local street fair or crafts show and have them try on rings there. Pay attention to the rings that end up fitting on them—if the size isn’t listed on it, you can ask the vendor what size it is and use that. You could also make them try on those costume rings with adjustable open backs and bring the adjusted ring to a jeweler.

5. Talk to them

Perhaps these creative methods aren’t for you—or maybe you’d rather be more direct about buying them a ring. In that case, the simplest way to figure out their ring size is just to ask them. The proposal can still remain a surprise if you ask about their ring size, anyway, if that is what worries you. After all, they still won’t know how you’re planning to do it or when you’ll pop the question. If you want, you can strike up the conversation with them while watching TV and prevent suspicion by bringing up the subject after a jewelry commercial comes on. This way, it seems more nonchalant and you can maintain some mystery about your proposal as well as find out more details about the engagement ring they want.