Rosary Bead Sizes When you see rosaries for sale online you will notice that the beads are typically measured in millimeters. Here is America we aren't too familiar with the metric system so the difference between 4mm and 10mm may not mean much to us. To help, we have created this rosary sizing guide so you can determine what bead size is best for you. 4mm beads are the smallest beads you will usually find on a rosary. These beads are very delicate and frequently seen on children's rosaries and rosary bracelets. 6mm - 8mm beads are the "standard" size beads you see for rosaries. Beads in this size range are sometimes carved or faceted. 9mm and larger beads are the perfect size to get for someone who likes carrying a substantial rosary or has arthritis. 20mm and larger beads are typically the size used for wall rosaries. You can download a printable rosary bead size chart we created with all the different sizes of beads in their actual sizes so you can compare.