Mike Dirnt's bass strings: the Green Day Precision rig, sourced
Documented bass-string gauges, brands, and tunings Mike Dirnt uses with Green Day on his Fender Precision Basses. Fender Super 7250 nickel-plated steel (.045 to .105) and Ernie Ball Cobalt Slinky bass strings. With citations.
Green Day · reviewed by the Change Your Strings editorial team ·
Mike Dirnt plays Fender Super 7250 nickel-plated-steel roundwounds (.045 to .105) on his fleet of vintage Fender Precision Basses, including 1960s and 1970s P-Basses such as 'Stella' (a 1969 P-Bass) and 'the Weapon' (a 1971 P-Bass). He is the founding bassist of Green Day, signed to Fender as a signature artist with the Mike Dirnt Precision Bass (originally launched in 2004 in the Artist Series, now offered as the Mike Dirnt Road Worn). Per Ernie Ball, he also uses Cobalt Slinky bass strings.
At a glance
Role
Active
Based
Notable credits
- Green Day, Dookie (1994)
- Insomniac (1995)
- Nimrod (1997)
- Warning (2000)
- American Idiot (2004)
- 21st Century Breakdown (2009)
- Saviors (2024)
Who Mike Dirnt is
Mike Dirnt (Michael Ryan Pritchard) is the founding bassist of Green Day, California pop-punk-into-arena-rock trio he formed in 1986 with Billie Joe Armstrong, completed by Tré Cool on drums in 1990. Green Day's catalog from Dookie (1994) through Saviors (2024) is one of the most commercially successful in punk-adjacent rock, Rock and Roll Hall of Fame inductee in 2015, multiple Grammy wins, and the American Idiot (2004) era that crossed Green Day into Broadway rock-opera territory. Dirnt's bass is the locked-pocket foundation underneath Armstrong's downstroke rhythm guitar.
Bass guitars
Signature production · Launched 2004 · Current rotation
Fender Mike Dirnt Road Worn Precision Bass
Modeled on the 1951 Precision Bass design with a 1955-style arm contour. Ash body, thick C profile maple neck, rosewood fretboard with 20 frets, Custom Vintage '59 split-coil P-Bass pickup, Badass II bridge. The original Artist Series signature ran from 2004 to 2014; the Road Worn iteration adds Fender's relic'd lacquer.
Source: Fender Mike Dirnt Road Worn Precision Bass product page; Reverb, 2004 to 2014 Artist Series profile.
Vintage stable · Named P-Basses
Vintage Fender Precision Basses including "Stella" (1969) and "the Weapon" (1971)
Dirnt's collection of vintage Fender P-Basses includes named instruments such as "Stella" (a 1969 P-Bass) and "the Weapon" (a 1971 P-Bass). Both are documented as strung with Fender Super 7250 .045 to .105 sets.
Source: Equipboard Mike Dirnt gear archive.
The wife-bought 1958 P-Bass · Stage rotation
Fender 1958 Precision Bass (Olympic White)
Documented in his 2023 Guitar World interview as a gift from his wife. "It eats my friends alive that I play it live," Dirnt told the magazine. The 1958 Olympic White P-Bass is one of the rarest finishes from that era; Dirnt has it on tour rotation, which is the most-cited counter-example to bass collectors who garage-keep their vintage instruments.
Source: Guitar World: Mike Dirnt on the '58 Olympic White P-Bass.
Strings
Documented standard · Factory-spec gauge · Verified use
Fender Super 7250 Bass Roundwound (.045-.105)
Fender's nickel-plated-steel bass roundwound, .045/.065/.080/.105. The standard Fender bass roundwound, same set Fender ships from the factory on most P-Basses. Documented across Dirnt's entire bass collection. Punchy mid-range, P-Bass split-coil bark, just enough top-end roundwound brightness to cut through Armstrong's downstroke rhythm guitar without veering into Rotosound stainless territory.
Source: Guitar World: Mike Dirnt interview, Equipboard: Mike Dirnt.
Secondary set · Documented by Ernie Ball
Ernie Ball Cobalt Slinky Bass
Per Ernie Ball's own social posts, Mike Dirnt also uses Cobalt Slinky bass strings to deliver his P-Bass tone. The Cobalt Slinky line offers a brighter, more articulate top end than the nickel-plated Fender 7250.
Source: Ernie Ball, Mike Dirnt and Cobalt Slinky bass strings.
Why this fits the rig
A Precision Bass with nickel-plated-steel roundwounds in standard .045 to .105 is a canonical pop-punk bass voicing: punchy mid-range, P-Bass split-coil bark, just enough top-end roundwound brightness to cut through Armstrong's downstroke rhythm guitar. The .045 to .105 gauge is also factory-spec for Fender P-Basses, which means Dirnt's setup and his tech's approach can use stock Fender setup specs without exotic gauge accommodations. His role on Green Day's catalog is steady eighth-note pulse with melodic fills, exactly the lane pop-punk bass occupies.
If you want this rig
Super 7250 Bass Strings, Nickel-Plated Steel Roundwound, Long Scale (.045–.105)
Why this one: Mike Dirnt's documented standard set. Factory-spec for Fender P-Basses, the exact lane Dirnt sits in. Punchy mid-range, P-Bass split-coil bark, just enough roundwound top-end to cut through Armstrong's downstroke rhythm guitar.
Endorsed vs. verified use
Dirnt is a documented Fender signature artist (Mike Dirnt Road Worn Precision Bass) and a verified Fender Super 7250 user. The endorsement and the use align: he plays Fender P-Basses, his signature is a Fender P-Bass, his strings are Fender, the production line of his signature has run for two decades. The Ernie Ball Hybrid Slinky Cobalt mention is verified-use rather than endorsed, a secondary set he reaches for when the song wants brighter top-end articulation.