Online Strobe Tuner
Play a note and watch the bands. They drift left when you are flat, right when you are sharp, and stop when you are in tune.
Note
—
Offset
—
Concert pitch (A4)
Every note is judged against this.
How to Read a Strobe Tuner
- Press Start microphone and allow access. Audio is analysed on your device and never uploaded.
- Play one string and let it ring. The large letter is the nearest note — the strobe is chromatic, so it works in any tuning.
- Watch the direction. Bands drifting left mean the note is flat: tighten the string. Drifting right means sharp: loosen it.
- The faster the drift, the further off you are. Make your turns smaller as the bands slow down.
- When the bands stand still and turn green, you are within a cent of the note.
Tune up to each note rather than down to it: if you overshoot, drop below and come back up. Approaching from below leaves the string wound tight around the tuning post, so it does not slip flat later.
What Makes a Strobe Different
A needle tuner tells you where the pitch is. A strobe tells you how fast it is moving away from the target. Real strobe tuners date from the 1930s: a disc printed with stripes spun at the exact speed of the target note, lit by a lamp flashing at the frequency of your string. When the two matched, the stripes appeared to freeze. Any difference made them drift, and the drift speed was the difference.
This page draws the same picture in software. It measures your note, works out how many cents it is from the nearest equal-tempered pitch, and moves the bands at a speed proportional to that offset. One cent off is a slow creep you can watch; ten cents is a brisk drift; fifty is a blur, which is when the number above the bands is more useful.
When to Use It
- Intonation. Compare the open string, or its 12th-fret harmonic, with the fretted 12th-fret note. Both should hold the bands still. If the fretted note drifts right, move the saddle back; if left, move it forward. The intonation checker walks through this string by string.
- Checking a setup after new strings, a truss rod adjustment or a tuning change, when you want more resolution than a needle gives.
- Any tuning, any instrument. Because it is chromatic, it works for Drop C, open G or anything else on the tunings chart. If you would rather have the target strings laid out for you, the standard guitar tuner does that.
Getting a Clean Reading
The strobe is only as steady as the signal it hears. Mute the strings you are not tuning, pluck firmly but not hard — a hard attack pushes the pitch sharp for the first fraction of a second — and hold the phone or laptop close to the guitar. Judge the bands once the note has settled. For the method and measurements behind the detector, see how accurate is this tuner.
Frequently Asked Questions
Is this as accurate as a hardware strobe tuner?
No, and we would rather say so. Dedicated strobe tuners are specified to a tenth of a cent. This page uses the same pitch detector as our main tuner, which we measured at under 2 cents of error per reading in quiet conditions. The strobe display makes small errors easier to see and the readout shows tenths of a cent, but it cannot make the microphone or the measurement more precise than that.
Why use a strobe display instead of a needle?
Because motion is easier to judge than position. A needle a cent or two off centre is hard to see, but a band creeping slowly across the screen is obvious, and so is the moment it stops. Strobe displays are favoured for setup work such as intonation, where you are chasing very small differences.
Why are there three bands moving at different speeds?
All three show the same error. The finer stripes move past faster for the same offset, so the bottom band picks up the smallest drift and the top band stays readable when you are further off. Mechanical strobe tuners have several rings for a similar reason.
The bands never stop completely. Is my guitar out of tune?
Not necessarily. A plucked string goes slightly sharp at the attack and settles as it rings, and every reading carries a little measurement noise. If the bands rock gently back and forth around a standstill rather than drifting steadily one way, you are in tune. Let the note ring and judge the steady part, not the pluck.
Can it tune a bass?
Yes. It listens down to about 24 Hz, below even a 5-string bass's low B (30.9 Hz). Phone microphones capture very little at these pitches, so play firmly and hold the phone close; the tuner often hears the string's overtones more than its fundamental and still reads the right note.