Guitar string gauges explained: what the numbers on your strings mean

A guitar string gauge is simply how thick the string is, measured in thousandths of an inch. The numbers printed on a pack, like 10 to 46, are those diameters. The set is named after its thinnest string, the high E, so a .010 set is a "tens" set and a .009 set is "nines."

Read a set as .010 to .046 and you are looking at the two ends: the high E at ten thousandths of an inch, the low E at forty-six, with the four strings in between filling the gap up to the wound low string (Ernie Ball). One number tells you so much because of tension. At a fixed tuning and scale length, a thicker string has to be pulled tighter to reach the same pitch, so a heavier set puts more total pull on the neck. That extra tension is what you feel and hear. It is the biggest decision you make about a guitar after the guitar itself, and the one variable you touch every second you play.

Gauge is an imperial measurement, but it converts straight to metric. One inch is 25.4 millimeters, so you multiply any gauge by 25.4 to get its diameter in millimeters. A .010 high E is 0.254 mm; a .046 low E is 1.168 mm. Here is the quick reference for the sizes you will actually meet.

The big US brands, Ernie Ball and D'Addario among them, label their packs in thousandths of an inch, which is why the inch numbers are the ones you see everywhere. Some European brands print the millimeter figure instead, so if a pack reads 0.25 or 0.30, that is a .010 and a .012 in metric. The strings are identical; only the ruler changed.

Need a gauge outside this quick list? Our full gauge chart runs every plain gauge from .007 to .026 and every wound gauge from .018 to .105, sourced straight from Ernie Ball's and D'Addario's own singles catalogs.

Electric sets sit on a short ladder from Extra Light .008 up to Heavy .012 and beyond. Standard tuning's default is the .010 to .046 Regular set. Go lighter for faster bends and a slinkier feel, heavier for lower tunings and a fuller voice. This chart lays out the whole ladder in one place.

The two ends are easy to reason about. A .009 set, like the Ernie Ball Super Slinky or D'Addario's EXL120, suits a light touch, fast lead playing, and effortless bends. A heavier .011 like the Power Slinky or D'Addario NYXL1149 gives you more body and holds tension when you tune down or dig in (D'Addario). In the middle, the .010 set is where most players live, which is why the Regular Slinky and D'Addario's NYXL1046 are two of the most-played sets on earth. If you are not sure, you are a tens player until proven otherwise, so start with a set like the Ernie Ball Regular Slinky. Only when you tune below D standard do you want to jump to a genuinely heavy set like the Ernie Ball Not Even Slinky Cobalt.

Acoustic strings use the same thousandths-of-an-inch system but run a little heavier than electric, and the size names differ. The common gauges are Extra Light .010 to .047, Custom Light .011 to .052, Light .012 to .053, and Medium .013 to .056. Light is the all-purpose default that most acoustics ship with and most players stay on.

The everyday acoustic default is a Light phosphor bronze set like D'Addario's EJ16, .012 to .053, warm and balanced across every style; D'Addario introduced phosphor bronze back in 1974 and it has been the standard acoustic wrap ever since (D'Addario). Reach for the D'Addario EJ16 if you want one set that covers fingerstyle and strumming. Step up to a Medium like the EJ17, .013 to .056, for maximum projection under heavy strumming, bluegrass flatpicking, or slide, but check your guitar can take it: Medium pulls roughly 25 pounds more total tension than Light. Prefer a softer touch or a small-body guitar? Drop to an Extra Light like the EJ10 in the brighter 80/20 bronze alloy. Our light vs medium acoustic guide settles that specific call.

Bass strings are much thicker and carry their own numbers. A standard 4-string set runs about .045 to .100, with a lighter .040 to .095 and a heavier .050 to .105 on either side. The logic is the same as guitar: heavier holds tension better for low tunings and hard playing, lighter feels looser and reads brighter.

The bass default is a Regular Light .045 to .100 nickel roundwound like D'Addario's EXL170, bright and even across rock, funk, and most everything else (D'Addario). The D'Addario EXL170 is the safe first set for a 4-string. Want more low-end weight and a tighter feel for drop tunings or a heavy pick attack? Step up to a Medium .050 to .105 like the EXL160. One thing to watch on bass: most sets are cut for a long 34-inch scale, so confirm the scale before you buy. Our best bass strings guide and the flatwound vs roundwound comparison go deeper on tone.

Gauge trades feel for tone, and that is the whole debate. Heavier strings pull more tension, so they sound fuller and louder and stay put under a hard pick, but they are stiffer to bend and fret. Lighter strings do the opposite: easy and bright, but thinner and looser. Here is what actually moves when you change gauge.

None of this makes one gauge better than another. It is a set of tradeoffs you tune to your hands and your music. The clearest proof is the pros: Stevie Ray Vaughan built a huge tone on very heavy strings around .013, while Tony Iommi wrote the heaviest riffs in metal on very light .008 gauges after a hand injury. Both were right, because both matched the string to the player. Our light vs heavy gauge guide runs the tradeoff in full.

Most players run a whole gauge, tens or elevens. But some of the most-discussed signature sets are really arguments about the gap between two rungs, where the honest answer for a specific player lived at a half-gauge nobody sells off the shelf.

John Mayer is the clearest case. His Silver Slinky is a .0105 set, bumped up half a gauge from a standard .010 across every string. A plain .010 slipped pitch under his sustained, vocal-style bends on a tremolo Strat, but a jump to .011 made the high strings fight him. He calls the gauge "perfectly situated" between the two, big enough for tone but nimble enough to finesse a bend (Guitar Player). Tim Henson of Polyphia took the opposite trick with his signature set: not a half-step up, but a hybrid, .0095 plain strings over wound strings that match a full standard bottom end (Ernie Ball). Light on top for fluid tapping, full underneath for chord body. Anna Cara, the guitarist covering Nita Strauss's touring chair in Alice Cooper's band, runs a similar hybrid on stage. Her S.I.T. Strings .010-.052 set stays standard on top and goes heavier on the bottom three, keeping the low end thick without stiffening her lead lines. It is the same idea behind every skinny top heavy bottom set: split the gauge decision in two and optimize each end separately.

The charts above assume standard tuning. The moment you tune down, the math changes, because detuning slackens every string. Drop your low E to D and a light set starts to feel loose; go to Drop C or Drop B and a standard gauge turns to spaghetti. Go heavier as you go lower to keep the strings at a firm, playable tension.

How much heavier depends on how far you drop. Drop D is gentle enough that many players stay on tens or step to elevens. Drop C and Drop B want a real jump, often an .011 to .052 or heavier, and frequently a skinny top heavy bottom set so the low strings get thick without making the leads stiff. Our string gauges by tuning chart maps every common tuning to its gauge, the Drop C gauge and tension chart runs the exact numbers, and for the lowest tunings the 7-string and 8-string gauge guides plus our baritone strings explainer cover the heavier hardware. Scale length matters here too: a longer neck holds more tension at the same gauge and pitch, which is why baritones and 7-strings can run a comparatively light gauge and still feel firm.

Start with the default and adjust from there. For standard tuning on an electric, a .010 set covers most players in most genres. Drop to a .009 if you want the slinkiest feel, play fast lead, or your hands tire on bends. Step up to an .011 if you tune to Eb or Drop D, strum hard, or want fuller chords. Go heavier still for Drop C and below.

Two honest caveats keep this from turning into a tone myth. First, gauge is mostly about feel and tension, not magic tone. It nudges the voice fuller or brighter, but most of your sound is in your hands, your pickups, and your amp, not in a half-thousandth of an inch. Second, change one thing at a time and give a new set a couple of weeks before you judge it; your hands adapt faster than you expect. When you are ready to match the gauge to your style, our what gauge should you use walkthrough and the gauge by genre guide narrow it down, and the whole catalog, sorted by brand and gauge, lives on the strings index. Need the exact diameter of a single string in millimeters? The guitar string gauge chart lists every plain and wound gauge in both inches and mm.