tune-o-matic.

Tune. Then intonate.

A free, guided tool for instrument setup: a tuner for 4, 6, 7 and 12-string instruments — guitars, bass, mandolin, ukulele (standard, drop and open tunings, 432–440Hz reference) — and a step-by-step intonation wizard for tune-o-matic and other adjustable bridges.

• Works with any microphone — but for best results, plug your instrument straight into the computer via an audio interface: a direct input gives a cleaner, steadier signal, so the needle locks on faster and reads more precisely. Pitch detection happens locally, no audio ever leaves your device.
• The tuner auto-detects which string you're playing, tracks every string with checkmarks, and supports common drop and open tunings derived from your chosen A4 reference (432–440Hz).
• The intonation wizard walks you through every step — "play the open string… now the 12th-fret harmonic… now fretted… it reads 6¢ sharp, so lengthen the string" — and iterates until every string converges.

The tutorial is fully simulated — no microphone, no audio access, nothing to plug in. Just watch the meter and follow along.

How intonation setup works

For each string: tune it → play the 12th-fret harmonic (always exactly double the open pitch — our reference) → play the same note fretted (reveals fret-placement error). Fretted sharp → lengthen the string; flat → shorten it. Small saddle turns, retune, repeat, done.

The physics, for the curious

Pressing a string down stretches it slightly, raising its pitch — so a mathematically perfect fret placement would actually sound sharp. Real bridges compensate by making the sounding length slightly longer than the scale length demands, which flattens fretted notes back into equal temperament.

The 12th-fret harmonic rings at exactly twice the open string's frequency no matter where the saddle sits, but the 12th-fret fretted note only matches it if the fret sits at the compensated midpoint. Comparing the two is the cleanest way to measure whether your saddle is in the right place.

One cent = 1/100th of a semitone. Below ±3¢ nobody can reliably hear the error, so that's our target.

Choose your input & setup

Pick where the guitar's sound comes from, your guitar, its tuning, and your reference pitch. An audio interface is the most accurate; a phone or laptop mic works fine in a quiet room.

Input device Default microphone Guitar 4-string (bass, mandolin, ukulele) 6-string 7-string 12-string Tuning

Input settings

Sensitivity — detection gate High — quiet signals, low interface gain, gentle picking Normal (default) Low — strong signals, loud room, ignore bleed

If notes only register on hard plucks, choose High. The level meter shows what the gate hears: it analyses only while the bar moves at all.

Advanced options — tolerances

All values in cents. Defaults shown in placeholders; leave a field empty to use the defaults. Your values are saved in this browser only. All tuning units are in ¢

Tuner: in-tune window

Wizard: pass tolerance

Wizard: "excellent" at

Wizard: open-string tune tol

Wizard: harmonic tol

Stability hold (ms)

Save tolerances Reset to defaults

After granting access, play something — you should see the level meter move and a waveform appear.

Why this step?

Tips for keeping it right

Intonation shifts as strings stretch and age, and even with temperature and humidity. Re-check after any restring or gauge change — it only takes a few minutes per string once you're comfortable.

If one string refuses to converge: check that string's action height (high action makes notes go sharp as you press harder), and look for a worn or misaligned saddle. And remember — after moving a saddle you must retune before re-measuring; the tool walks you through that loop.