9s vs 10s: which should I actually buy?

"9s" and "10s" name the gauge of the high E string in thousandths of an inch — .009" versus .010" — and the whole set scales up or down with it. Run through this site's own reference sets for a 6-string electric in standard tuning: a 9-gauge Super Light set totals about 85.1 lbs of tension across all six strings, and a 10-gauge Regular Light set totals about 103.5 lbs — an 18-lb difference spread across the whole neck for what is, string to string, often well under a tenth of a millimeter of added diameter per string.

That 18 lbs is not evenly distributed in its effect. It is most noticeable in two places: how much finger pressure a bend takes (a half-step bend on a 10-gauge B string takes real, measurable extra force compared to a 9-gauge one, which is why lead players who bend constantly often prefer 9s or even lighter), and how the guitar's neck and top respond structurally to sustained higher tension over months of tuning (a neck that was set up and intonated for 9s can need a truss-rod and action adjustment after a permanent switch to 10s, because the neck genuinely bows slightly differently under 18 more pounds of pull).

Beyond bending effort, the practical differences are smaller than the tension number alone suggests: both gauges are entirely normal, widely stocked, factory-default choices — Fender ships many electrics with 9s, Gibson often with 10s — and neither is a "beginner" or "expert" gauge. Tone differences exist (10s generally read as a touch fuller and less prone to fret buzz at a given action) but are smaller than pickup choice, amp settings, or technique, and are easy to overstate in either direction.

The practical decision rule: if lead bending technique — half-step and whole-step bends up around the 7th-12th fret, vibrato — is central to how someone plays, 9s make that technique physically easier and are the more common lead-guitar default. If rhythm playing, lower tunings, or a heavier pick attack without much bending is the main use, 10s hold up under harder strumming and resist fret buzz slightly better at a given action height. Neither answer is wrong, and switching between them is a cheap, reversible experiment — not a commitment that requires new gear.