Tune your guitar or bass using your microphone or by ear
Guitar Scribble's free online tuner gives you two ways to get your acoustic guitar, electric guitar, or bass guitar perfectly in tune — automatic microphone detection or tune-by-ear reference tones. Both modes support over 15 alternate tunings for guitar and multiple bass tunings, plus adjustable reference pitch from A=415 Hz to A=466 Hz.
Click "Start" and play any open string. The tuner listens through your device's microphone, detects the pitch in real time, and shows you exactly how sharp or flat you are on the needle gauge. The needle responds continuously with minimal latency, giving you instant visual feedback as you turn the tuning peg. When the needle sits in the green center zone, your string is in tune. The tuner automatically identifies which string you're playing based on your selected tuning.
Our online tuner is perfect at home, but for gigs and jam sessions a clip-on tuner is a must-have. We've tested and compared the best options.
See our recommended tuners →Switch to "Tune by Ear" mode and tap any string button to hear its correct reference pitch. Choose between acoustic guitar, clean electric guitar, and bass guitar tones — each generated using physical modeling synthesis that simulates how a real plucked string vibrates and decays. This is the traditional way guitarists have tuned for decades — listen to the reference note and adjust your string until it matches.
Select "Bass" to switch to 4-string bass guitar mode with standard bass tuning (E-A-D-G), Drop D, and other common bass tunings. The tuner adjusts its frequency detection range to accurately read the lower frequencies of bass strings, and the tune-by-ear mode produces deep, authentic bass tones.
This tuner works as a Progressive Web App (PWA), which means you can install it directly to your Android or iOS home screen and use it just like a native app — no app store required. On Android, open this page in Chrome and tap "Add to Home Screen" from the browser menu. On iPhone, open in Safari, tap the share button, and select "Add to Home Screen."
While standard tuning (EADGBE) is where most guitarists begin, alternate tunings open up entirely new chord voicings, resonances, and musical possibilities.
The most common alternate tuning, Drop D lowers the 6th string by one whole step. This creates a deep, powerful low D that enables easy power chords with a single finger barre across the lowest three strings. It's a staple in rock, metal, grunge, and folk music.
Every string is tuned down one semitone from standard. Popularized by guitarists like Jimi Hendrix, Stevie Ray Vaughan, and Slash, half step down tuning reduces string tension slightly, making bends easier while giving the guitar a darker, heavier tone.
All strings drop a full whole step. This tuning delivers an even deeper, sludgier tone and is popular in heavier rock and metal genres. It pairs well with heavier gauge strings to maintain good tension.
These tunings combine a lowered bass string with a half or whole step down across all strings, giving you the easy power chord shapes of Drop D in a lower register. Widely used in modern metal and hard rock.
Open tunings tune the guitar so that strumming all open strings produces a major chord. They're essential for slide guitar, Delta blues, and certain folk styles. Keith Richards famously uses Open G for many Rolling Stones songs.
A suspended tuning that produces a rich, droning quality. DADGAD is widely used in Celtic, folk, and fingerstyle guitar music. It creates beautiful open-string resonance that works wonderfully for modal and ambient playing.
The question of what frequency the note "A" should be tuned to has been debated by musicians for centuries. Today's standard of A=440 Hz is surprisingly modern — and the journey to get here was anything but straightforward.
Prior to the 19th century, there was no coordinated effort to standardize musical pitch. The frequency of "A" varied wildly from city to city, church to church, and even decade to decade. A Venetian church organ might be tuned with A near 460 Hz, while a German cathedral organ of the same era might sit around 415 Hz — nearly a semitone lower. English cathedral organs in the 17th century could be pitched as much as five semitones lower than a domestic keyboard instrument in the same city. When traveling musicians moved between courts and concert halls, they often had to transpose entire performances on the spot.
In 1711, English musician John Shore invented the tuning fork, giving musicians their first reliable, portable pitch reference. A surviving tuning fork associated with Handel from 1740 is pitched at A=422.5 Hz, while a specimen from 1780 reads A=409 Hz — illustrating that even with tuning forks, there was no agreement on what frequency to settle on.
Through the 18th and 19th centuries, concert pitch crept steadily upward as orchestras and opera houses competed for the brightest, most brilliant sound. Higher pitch meant brighter tone — and audiences responded. An 1815 tuning fork from the Dresden Opera gives A=423.2 Hz; just eleven years later, one from the same opera house reads A=435 Hz. At La Scala in Milan, A rose as high as 451 Hz. By the 1850s, opera singers began complaining bitterly of vocal strain from the relentless rise in pitch.
In response to singers' protests, the French government convened a commission that included composers Hector Berlioz, Gioachino Rossini, and Giacomo Meyerbeer. On February 16, 1859, France passed a law establishing A=435 Hz as the "diapason normal" — the first government-mandated pitch standard in history. Queen Victoria sanctioned its use for her private band in 1885, and Britain's Royal Philharmonic adopted a similar A=439 Hz standard in 1896.
Even before the French standard, German physicist Johann Heinrich Scheibler had pioneered the scientific measurement of pitch. Using his "tonometer" — a set of 52 tuning forks spanning a full octave — Scheibler measured frequency with remarkable precision. In 1834, he recommended A=440 Hz at a meeting of the Society of German Natural Scientists and Physicians in Stuttgart. This recommendation quietly influenced instrument manufacturing for the next century, particularly in America, where the music industry informally standardized on A=440 Hz by 1926.
By the early 20th century, the patchwork of standards had become unworkable. In 1939, an international conference in London agreed that A=440 Hz would become the worldwide standard — a compromise between the French tradition of A=435 Hz and the higher pitches common in Anglo-American practice. Mathematician Sir James Swinburne argued for 440 partly because it simplified calculations compared to 439, a prime number. The BBC then began broadcasting an A=440 Hz tuning tone generated by a piezo-electric crystal oscillator, helping spread the standard across the airwaves.
The International Organization for Standardization formally adopted A=440 Hz in 1955 as ISO 16, and reaffirmed it in 1975. Despite this, concert pitch continues to drift upward in some contexts. A 1987 New York Times survey found that most professional orchestras tuned between A=440 Hz and A=444 Hz. The Berlin Philharmonic and Vienna Philharmonic often tune to A=443 Hz or higher. Highland bagpipe bands play at a dramatic A=470–480 Hz — over a semitone above the standard.
Period-instrument ensembles performing Baroque music typically tune to A=415 Hz for historical authenticity. The "A=432 Hz" movement has gained a following among some modern musicians who claim this frequency has special mathematical or natural properties. Giuseppe Verdi advocated for a similar pitch (C=256 Hz, yielding approximately A=430.5 Hz), but this "scientific pitch" never received wide official adoption, and the specific claims about 432 Hz being uniquely "natural" or "healing" lack scientific support.
Playing in tune is the foundation of good guitar playing. Even slight detuning causes chords to sound muddy, harmonics to clash, and your playing to sound amateurish regardless of technique. Regular tuning also trains your ear to recognize pitch relationships, which accelerates your overall musical development.
Tune your guitar every time you pick it up, and check your tuning periodically during practice sessions. Temperature changes, string stretching, and playing intensity all cause guitars to drift out of tune. New strings are especially prone to detuning and may need to be retuned several times during their first few hours of play.
