Order custom-size press-ons with a separate size for each finger, using the method requested for that exact set. A custom order gives the maker information to select tips; it does not automatically guarantee that every curve will match your natural nails.
Allow time to check the fit before an important event. If a sizing kit is available, it can make this conversation much more concrete.
Confirm which tips the size chart describes
Choose the shape and length first. Then check that the chart or sample kit applies to that combination. The same size number can refer to a different width or curve in another style, even within one shop.
Ask whether the order takes millimeter measurements, molded tip numbers, or a preset size group. Those are different forms of information. Do not send a mixture of them without explaining what each number means.
Record both hands separately
Make two clearly labeled lists in the requested order. For example, write “Left: thumb, index, middle, ring, little finger,” followed by the corresponding sizes, then repeat for the right hand.
Measure or try on every finger. Matching fingers on opposite hands can differ. If you repeat a measurement and get conflicting results, resolve it before ordering rather than averaging numbers that may have come from different positions.
Use a sizing kit as a fit check
Try the sample tip without adhesive. Check coverage from side to side, the shape near the cuticle, and whether the tip rests comfortably without being forced flat. Look from the end of the finger as well as from above.
Write down the size that fits, along with the tip style. If one sample is too narrow and the next is too wide, ask about the maker’s recommended adjustment. Filing may help a small outline mismatch, but it does not reliably change the curve of the whole shell.
Describe exceptions in plain language
A short note such as “My right thumbnail is flatter than the sample” is more useful than choosing a smaller size to make it grip. If requested, send a well-lit photo showing the issue, without adhesive hiding the contact area.
Keep medical concerns out of the sizing experiment. A sore, damaged, or visibly changed nail needs attention before it is covered. A custom cosmetic fit cannot resolve the underlying problem.
Confirm the order before production
Review the shape, length, color, decoration placement, and ten-finger size list together. Check how the seller handles replacement nails and whether a later order can use the same saved record. Keep your own copy in case the style changes.
On arrival, match the tips to that record and dry-fit them again. Save any successful adjustment as a note for the next order. Label it with the exact style and date, so an old size list does not become an unexplained string of numbers.