If you’re shopping for an engagement ring, you’ll want to get the right size – or something close to the right size that can be resized later. But at the same time, you may want to keep your purchase a secret. Asking your partner outright about their ring size could inadvertently reveal your intentions, thus ruining the surprise of popping the question.

So how can you discreetly determine your partner’s ring size?

Option 1: Measure Your Own Ring Size and Compare

First, there are many different ways you can measure ring size at home. If you have flexible measuring tape, you can use it to measure the circumference of your finger and use that to determine which ring size would best fit you. If you don’t have that available, cut a piece of dental floss to fit around your finger and measure that.

Then, compare your finger size to your partner’s finger size. Does it seem significantly bigger or smaller? Is it approximately the same size? This may be hard to do discreetly, so consider holding hands so your fingers are in direct alignment.

Obviously, this is a method of estimation that’s not going to provide you with perfect results. Fortunately, there are alternative options available.

Option 2: Find an Existing Ring

Does your partner wear rings on a regular basis? If so, find a ring that they’ve worn on their ring finger in the past. When they’re not around, use a printable ring size chart to figure out the size of the ring. Depending on the piece of jewelry, it may even be printed or etched on the ring itself. This way, you can be reasonably confident that the size is correct.

If you’re on a time crunch, or if you can’t borrow the ring for an extended period of time, consider using pencil and paper to take a tracing of the inside of the ring.

Option 3: Ask a Friend or Family Member

Your next option is to ask a friend or family member for some help. Call up one of your partner’s friends and ask them for some help. There’s a chance they may immediately know your partner’s ring size from prior experience. If so, you can get fast information and move on with the remaining steps of your purchase.

If they don’t know, you’ll need to take some extra steps. The simplest approach is to have this friend ask your partner about their ring size directly. Depending on the context, this could be seen as innocuous, not raising any alarms. You could also ask the friend to have your partner try on one of their rings to see how it fits. Again, this may require some finesse so as not to seem suspicious.

Of course, this option depends on your trust in the friend or family member in question. Do you believe that they’ll be able to keep the secret, or are they going to spill that you’re going to propose in the near future? If you don’t know your partner’s friends or family members especially well, or if keeping the surprise is a top priority, this may not be the way to go.

Option 4: Pretend You’re Buying Something for Someone Else

If you feel confident lightly deceiving your partner, you could pretend you’re buying a ring for someone else. For example, you could pretend to be buying a ring for your mother; simply explain to your partner that their fingers are similar in size to your mother’s (if this is accurate) and get their ring size so you can, presumably, ballpark the right sized ring for your mother.

This can obviously work if you’re buying a ring for anyone else, but family members tend to inspire less jealousy.

Option 5: Give Up on Being Discreet

Your final option is to give up on being discreet. It’s nice to consider the idea of surprising your partner with a proposal, but in many cases, it’s better to have an outright conversation about engagement before popping the question. Doing so will ensure that you and your partner’s goals are aligned and that you’re both interested in eventually getting married.

Asking about your partner’s ring size may spoil the surprise that you plan on purchasing them a ring, but the rest of your proposal can still be a total surprise; they don’t have to know any other details about when or how you’re going to ask them to marry you.

Ultimately, there are many different ways to learn your partner’s ring size, with various degrees of discreetness. Try not to worry too much about this decision; you can always resize the ring at a later date if it doesn’t fit perfectly initially.