Strobe Tuner Online
This strobe tuner online shows pitch the way a bench strobe tuner does: instead of a needle, a ring of light and dark bands drifts left when the note is flat and right when it is sharp. The bigger the error, the faster it spins; when the note is in tune, the ring stands still. Below it you get the note name, the cents to one decimal (for example +3.4 cents), the frequency to two decimals and a stability indicator that tells you how much the reading is wavering. Everything runs in your browser, free, with no account and no audio leaving your device.
How to use it
- Tap Turn on microphone and allow access. Keep the device close to the instrument in a quiet spot.
- Play a note and let it ring. The ring drifts left if the note is flat and right if it is sharp; tune up or down until it stops and the number turns green.
- To tune one string without the tuner jumping to the neighbouring note, pick it under Target note: the ring then compares only with that note, in any octave.
- Check the Reference A (440 Hz is standard; many orchestras use 442) and, for a transposing instrument, choose B♭, E♭ or F under Transposition.
- Open Cents → Hz for this note to see how many hertz 1, 2, 5 or 10 cents are worth on the note you are playing; hold the last reading keeps the result on screen after the sound stops.
Help and explanations
It is for anyone who needs more than a regular chromatic tuner: luthiers setting intonation on a guitar or bass, piano, accordion and harmonica technicians, wind players checking a tuning slide, and anyone curious to watch how much a string drifts as it decays. The readout is a moving average of the last microphone readings with outlier rejection, which keeps the number steady enough to read a tenth of a cent.
What is a strobe tuner and how does it work
The original strobe tuner had a striped disc spinning at a fixed speed, lit by a lamp that flashed at the frequency of the note picked up by the microphone. If the note was exactly right, the disc looked frozen; if it was slightly flat or sharp, the stripes appeared to creep one way or the other. Because the eye catches that motion long before a needle moves, the strobe became the tuner of choice for luthiers and piano shops.
Here the ring is drawn on screen and rotates at a speed proportional to the error in cents measured from the microphone: one cent of error moves one band of the outer ring every two or three seconds; ten cents make it spin fast. The three rings turn at different speeds (the inner one four times faster) so both tiny and large errors are easy to see.
How accurate is it really
The readout shows tenths of a cent, but the real accuracy depends on your microphone, the room noise and the instrument. On a stable string or a sustained sound (winds, a steady voice, a tone generator) the reading typically wanders by about ±0.5 cent; the stability indicator shows exactly how much it is moving. A guitar string changes pitch as it decays, because tension drops slightly after the attack: read the cents a second after you pluck, not at the moment of the pick.
For scale, on A4 (440 Hz) one cent is 0.25 Hz, and on a guitar's low E (82.41 Hz) it is under 0.05 Hz. The Cents → Hz for this note table does that math for whatever note is on screen. Most people start hearing a pitch difference between two consecutive notes at around 5 cents; below that you are in setup territory, not listening territory.
For luthiers: intonation and setup
To check intonation on a guitar or bass, lock the target note to the string you are measuring, tune the open string until the ring stops, then play the 12th-fret harmonic and the fretted note. If the fretted note reads sharp (ring drifting right), the vibrating length is too short and the saddle must move back; if it reads flat, move it forward. Since the tuner compares against the note class in any octave, the harmonic and the fretted note share the same reference.
Tips
- Use Target note on low strings: the microphone sometimes locks onto the second harmonic, and with the target locked the reading stays on the right note even if the octave flips.
- Let the note ring on its own. A hand resting on the body, a fan or people talking nearby all hurt stability; when the indicator turns red, the reading is not reliable.
- On instruments whose pitch changes with breath or picking strength, tune to the average sound you actually play with, not the loudest you can produce.
- For a quick sanity check, play a 440 Hz A on the tone generator on another device: the reading should settle on A4 with cents close to 0.0.
Frequently asked questions
What is the difference between a strobe tuner and a regular tuner?
A regular tuner shows a needle with 1 cent resolution and smooths the reading heavily so the needle does not shake. A strobe tuner shows the motion of the ring and the cents to a tenth, so you can see errors smaller than 1 cent and watch the note change while it sounds. For tuning before a gig both work; for setups and lutherie the strobe shows more.
Is this as accurate as a bench strobe tuner?
No. A professional strobe with a cable input reads 0.1 cent or better. Here the measurement comes from a phone or computer microphone, and the reading settles to about ±0.5 cent on a sustained note. That is far more than a regular tuner gives you, but if you need certified accuracy, use a dedicated unit.
Why does the ring never fully stop?
Because the actual note is changing. Strings decay and lose a little tension, winds waver with the air stream and voices have vibrato. Aim for the slowest drift you can get and look at the cents: if they stay between −1.0 and +1.0 and the number is green, the note is in tune for any practical purpose.
What does the stability indicator mean?
It shows how much the last readings differ from each other, in cents. ±0.2 means the reading is solid; ±3 means the sound is wavering or there is noise, and in that case the cents value does not mean much.
Can I use it with B♭, E♭ or F instruments?
Yes. Choose the transposition and the tuner shows your instrument's written note (a trumpet playing written C shows C, not B♭). The reference A still applies to the actual frequency.
Does it work for tuning a piano?
It works for checking notes and measuring how many cents a string is off. Tuning a whole piano requires temperament and an inharmonicity curve, which this tuner does not calculate; it helps you measure, it does not replace a piano tuning app.
Is the audio recorded or uploaded?
No. The analysis happens in the browser on your device; nothing is recorded or sent to a server.