Measure First
First, measure your natural nail width.
Press-on nail sizes are based on the widest part of your natural nail. Use a soft tape measure, ruler, paper, or tape, and measure along the natural curve of your nail.
Soft tape measure Place it along the nail curve and measure from side to side.
Ruler Align it with the widest part of your nail and check the width.
Paper Wrap it over the nail, mark both sides, then measure the marked width.
Tape Place it on the nail, mark both sides, remove it, then measure the width.
When using paper or tape, keep it close to the nail curve without lifting it. If it is tilted or too loose, the measurement may be larger than your actual nail width.