7-string guitar string gauge guide: the tension math for B standard, Drop A, and extended lows
Reviewed by the Change Your Strings editorial team ·
For a 7-string in B standard (B-E-A-D-G-B-E) on a 25.5-inch scale, .010–.059 is the floor, Ernie Ball Regular Slinky 7-string or D'Addario NYXL 10–59. Step up to .010–.062 for Drop A, .011–.064 for Drop G#, .012–.068 for Drop F#. Longer 26.5–27-inch scales let you drop one gauge lighter; shorter 25.5-inch scales may require stepping up to keep the low string articulate under gain.
The one-paragraph answer
Tune your 7-string to B standard on a 25.5-inch scale? Use .010–.059. Drop to A? Step up to .010–.062. Lower than that, Drop G#, Drop G, F# standard, keep stepping up gauges, a whole step of tuning drop for every gauge step heavier. Scale length modulates everything: 26.5-inch and 27-inch scales let you run one gauge lighter than a 25.5-inch reference for the same feel. If you're in B standard on an Ibanez 8-string scale (27"), a .010–.056 can actually work.
The tension targets, 7-string low B
The 7-string's defining string is the low B (or low A for drop-tuned material). That's the string that has to do the work the 6-string's low E does in standard tuning. Gauge math around that note dictates the rest of the set.
For Drop A on 25.5-inch, replace the low B target with a low A at .062 (~16 lbs) or .064 (~17 lbs). For Drop G#, use .064 or .066. For F# standard on a 7, rare but seen, .068 or .072 is the low-string gauge range, which starts bumping into 8-string territory.
The 7-string sets that actually ship
Stock 7-string sets, ranked by use case
Pick by tuning
Per-tuning gauge floor on 25.5-inch scale
Pick by scale length
A 27-inch scale 7-string (Kiesel, Jackson Pro Series baritone-7, some multi-scales at the low end) effectively lets you run one gauge lighter than a 25.5-inch guitar in the same tuning. A low A at .060 on 27-inch feels similar to a low A at .064 on 25.5-inch. This is the trade most extended-range metal players make: longer scale + lighter gauge = cleaner articulation at low tunings without the finger-fatigue of the heaviest gauges.
A 24.75-inch Gibson-scale 7-string (Les Paul Studio 7, some ESP LTD 7s) is the opposite. Shorter scale means you need to step up a gauge over the 25.5-inch reference to get equivalent tension, which compounds the stiffness problem the short scale is supposed to solve.
The 7-string Cobalt set most pros pick
Slinky Cobalt 7-string (.010–.062)
Why this one: The 7-string Cobalt gauge Mark Holcomb uses for Periphery. Low .062 holds Drop A and Drop A# cleanly; Cobalt wrap keeps the low string articulate under high gain on passive humbuckers.
Install notes specific to 7-string
Setup-adjustment checklist for 7-string gauge changes
The full setup walk-through applies. See the heavy-gauge install guide for the truss-rod and saddle-height check sequence, and the precision nut filing guide for the slot-cut procedure.
Related
- 8-string, not 7-string? See the 8-string gauge guide and 8-string high-tension setup
- Who's on 7-string? Top 10 7-string players and individual rigs of Mark Holcomb, Keith Merrow, Jason Richardson, Tosin Abasi
- Tunings: B standard, Drop A
- The cross-wire pillar: String gauge and scale length reference
- Comparison: Cobalt vs nickel Slinky
Frequently asked questions
What's the standard gauge for a 7-string guitar?
B standard, 25.5-inch scale: .010–.059. The factory-default reference set across Ernie Ball, D'Addario, and Elixir, ships on most Ibanez / Schecter / Jackson 7-strings. Below B standard, step up one gauge per whole step down.
Do 7-string guitars need a different scale length?
Not strictly, but longer scale lengths help. The 25.5-inch Fender scale works for B standard; most modern 7-strings (Ibanez RG7, Schecter SLS Elite) use 25.5" for familiarity. 26.5-inch (Mayones, Schecter extended) and 27-inch (Jackson Pro Series Soloist 7, Kiesel multi-scale) add tension on the low B, letting you comfortably run lighter top-string gauges.
What gauge for Drop A on 7-string?
25.5-inch scale: .010–.062 minimum for Drop A. The low A at .062 produces about 16 pounds of tension. Mark Holcomb's Cobalt 7-string is .010–.062. On 26.5-inch scales, .010–.059 works if your touch is lighter.
Is there a difference between 7-string nickel and 7-string Cobalt?
Same as 6-string. Cobalt gives 2–3 dB more output and tighter low-end articulation through passive pickups. For 7-string rhythm work in B standard or lower, especially under high gain, Cobalt's extra definition helps the low string read as a note rather than a rumble. Most extended-range metal players who care about this pick Cobalt (Mark Holcomb, Keith Merrow) or an equivalent.
Can I put a 7-string set on a 6-string guitar?
No. 7-string sets have seven strings with a specific low-B or low-A gauge that has no home on a 6-string bridge or nut. If you're trying to tune a 6-string down to A or B, you need a dedicated baritone 6-string set (.013–.062 or similar) and probably a longer-scale guitar. See the heavy-gauge install guide for the setup implications.
Which 7-string set is best for Periphery / djent-style rhythm work?
Mark Holcomb runs Ernie Ball Cobalt Slinky 7-string .010–.062 for Periphery's Drop A#/A work. Misha Mansoor uses D'Addario NYXL 10–59 and custom gauges for B standard / Drop G# material. Djent-specifically: gauge floor is .010–.062 on 25.5-inch scale, stepping up to .011–.064 or .012–.068 for the lowest Meshuggah-adjacent tunings.
What tunings are common on 7-string?
B standard (B-E-A-D-G-B-E) is the default. Drop A (A-E-A-D-G-B-E) drops the low B to A for Dream Theater / Periphery / Animals as Leaders-adjacent material. Drop G# and Drop G are heavier. A few players use Drop F# to push into 8-string territory without switching instruments, though most of those players eventually move to 8-string.
Do 7-string strings cost more than 6-string?
About 20–30% more per set. Ernie Ball 7-string Regular Slinky runs roughly $7–9 vs $5–6 for a 6-string equivalent. 7-string Cobalt and Paradigm sets are proportionally more expensive. The cost math still favors single-set 7-string rigs over maintaining a second 6-string tuned permanently to Drop A.