To determine the proper sleeve size, measure the armhole circumference of the dress. It’s important to measure the seam line where the old sleeve was previously stitched, not the fabric edge (since armholes are curved, the edge will yield an inaccurate measurement).
There is some overlap in armhole measurements between the Girls and Ladies size ranges. Where both fit the measurement, we recommend the Girls sizes for prepubescent figures or those under 63 inches in height. We recommend the Ladies sizes for teens and adults, or those taller than 63 inches.
Armhole measurement: 11.25-15.5 inches / 28-39 cm
Sleeve length: 15-23 inches / 39-58 cm
Armhole measurement: 14.5-18.5 inches / 37-47 cm
Sleeve length: 23.5-25 inches / 60-64 cm
Armhole measurement: 17.75-22.5 inches / 45-57 cm
Sleeve length: 25-26.5 inches / 63-68 cm