How to Measure Ring Size with Your Phone: A Step-by-Step Guide

Solution: This is normal with manual measuring. Repeat your measurement three times and take the middle reading as your official size. If all three readings differ by more than half a size, ensure you're measuring correctly—consistent inconsistency points to technique issues.

Solution: Clean your phone screen with a soft cloth to remove dust and oils. Press the ring flat against the screen with gentle downward pressure. Measure in a well-lit room without glare. If your phone case is raised, you may need to remove it temporarily to get a flat surface.

Solution: Choose the larger size if you prefer wider band rings or thicker bands, as these will feel tighter. Choose the smaller size if you prefer thinner bands or delicate rings. If you're buying an engagement ring, consider comfort fit rings which are slightly roomier, and size up if between sizes.

Solution: This is completely normal. Fingers swell during the day due to temperature changes, activity level, and hydration. Always measure in the evening at room temperature when your fingers are at their largest. This ensures your ring will fit comfortably throughout the day.

Solution: Use the string method to measure your finger directly, then cross-check your result with the Ring Sizer app using a friend's ring or by visiting a jewelry store to confirm. This two-method approach gives you confidence in your measurement.

How accurate is measuring ring size on a phone?

Within 0.25-0.5 size when using an app with screen calibration. The Ring Sizer app calibrates to each iPhone model for sub-millimeter accuracy. This level of precision is typically accurate enough for purchasing rings online. The Ring Sizer app achieves accuracy comparable to professional jewelry store sizing tools because it accounts for your phone's specific screen technology and resolution.

Can I measure ring size without an existing ring?

Yes, use the string or paper method around your finger, then check the circumference against a size chart. While this method works, having an existing well-fitting ring to measure with the app is more reliable because you're measuring a known object rather than estimating finger dimensions. If you don't have a ring, ask a friend or family member if you can borrow one that fits a similar size finger.

Does this work on Android phones?

The Ring Sizer app is currently iOS-only. Android users can use the string method and reference our ring size chart for conversion. We're working to bring the Ring Sizer app to Android in the future. In the meantime, the string method is equally reliable when done correctly.

Should I measure my ring size in the morning or evening?

Evening is better. Fingers swell slightly during the day and are at their largest in late afternoon or evening, typically about 0.5-1 size larger than in the morning. Measuring when your fingers are at their largest ensures your ring will fit comfortably throughout the day. Avoid measuring first thing in the morning or after exposure to cold, as your fingers will be slightly smaller.