So you're ready to pop the question and now all you need is an engagement ring to deliver the perfect proposal. In addition to knowing your partner's preferences when it comes to her future ring (gold or platinum? Side stones or pavé?), one major piece of information that's pertinent to have is her ring size. However, asking her straight-out would ruin any chances of a surprise proposal. If you intend on popping the question as a surprise, you'll have to determine her ring size without her suspecting anything. To ensure your proposal remains under wraps, we've outlined how to get your partner's ring size without asking.

Below are eight tips for sneakily figuring out just what ring size will fit on her finger.

1. Phone a friend

If you two have already discussed marriage as a possibility in your future together, chances are she's spilled her ring size (and style preferences) to a close friend or relative. Reach out to someone you can trust not to blow your cover and see if they might be privy to this information.

2. Use a ring sizing gauge

If she's a really deep sleeper, you may even get away with using our ring sizing gauge ($9.50) on her finger while she slumbers. This will be as accurate of a measurement as you can get without visiting a professional jeweler to get sized. Again, be sure not to tighten it too much as this will give an inaccurate measurement (and might wake her up).

3. Hold her hand

This isn't the most accurate method but it can be a start if there are no other options. The next time the two of you are holding hands, see if you have a finger that's similarly sized to her ring finger.

4. Use some guesswork

The average woman's ring finger is a size 6, so you can use this fact to assess where on the scale your partner's finger might fall. If she has smaller hands or slender fingers, she's probably smaller than a size six and vice versa.

5. Err on the larger side

It isn't the end of the world if you need to get the engagement ring resized after the proposal. If you don't have a precise measurement, it's advised to size up, rather than down—since resizing is then easier to do and it guarantees she'll be able to put the ring on for the momentous occasion.

Finally figured out your partner's ring size? Connect with a Ring Concierge Bridal Specialist to help you with the rest.