What ring size should I guess for a surprise proposal?

Most women in the US are a size 6 or 7. If she is average build, guess 6.5. If she is petite, 5.5-6. If she has larger hands, 7. You can also borrow a ring she wears on her ring finger and press it into a bar of soap to make an impression.

In 2026, solitaire with a thin band and hidden halo is dominating. Classic prong settings (4 or 6 prong) never go out of style. Bezel settings are popular for active people. Pavé bands are everywhere but pick good prongs or stones fall out.

Americans wear engagement and wedding rings on the left hand, ring finger (third from thumb). This comes from the old 'vena amoris' belief. Some cultures wear on the right. In the US, left is the default.