Use the free Guitar Tuner by Ear below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
Two Ways to Tune, One Honest Tool
Every guitarist faces the same moment: a string sounds wrong, and you need it right before you play. There are two classic ways to fix it. The first is tuning by ear to a reference tone: you play a known pitch, then turn the tuning peg until your string matches it. The second is using a tuner that listens and tells you how sharp or flat you are. This tool gives you both, in one browser page, for free, with no app to install.
Start with the reference tones if you are learning. Standard tuning, from the lowest string to the highest, is E, A, D, G, B, E. Press the E2 button and listen to the low E tone. Play your low E string and compare. If your string sounds lower than the tone, tighten the peg slowly. If it sounds higher, loosen it. When the two sounds blend into one, with no slow wobbling beat between them, you are in tune. Repeat for each string. This is slow at first and fast with practice, and it trains your ear in a way that staring at a tuner screen never will.
Using the Microphone Tuner
Press Start microphone tuning and allow access when your browser asks. Play one string cleanly, on its own, and let it ring. The tool listens through your microphone, analyzes the sound, and shows the nearest note, the exact frequency, and how many cents sharp or flat you are. One hundred cents is one semitone, so plus twenty cents means you are one fifth of a semitone sharp. Tighten or loosen the peg in small steps, play again, and watch the number move toward zero.
Play one string at a time, and mute the others with your fretting hand. If two strings ring together, the tool may lock onto the louder one or jump between them, and the reading will confuse you. Play near the microphone, in a quiet room, and let the note ring rather than picking it repeatedly. A clean, sustained note gives the analysis the best chance of being right.
How Pitch Detection Works
The tool uses autocorrelation, a classic and honest method. It takes a short slice of your sound and compares it against delayed copies of itself. When the delay matches the period of the wave, the copies line up and the match score peaks. That peak delay gives the frequency. It is simple, transparent, and effective for a single clear note. It is also sensitive to harmonics, which are the extra tones a guitar string produces above its main pitch, and to background noise, which adds false matches.
That sensitivity is why the accuracy limits are stated plainly on the tool. In a quiet room, with one string played cleanly, detection is usually within a few cents. With background noise, other strings ringing, a weak phone microphone, or a very bright-sounding string with strong harmonics, the reading can shift by ten cents or more. Ten cents is audible to a careful ear but small in musical terms: many live performances drift by that much. Treat the microphone reading as a guide, confirm by ear against the reference tone, and you will tune well.
When the Microphone Is Blocked
Browsers protect the microphone for good reason, and some users prefer not to grant access at all. If access is denied, the tool says so clearly and the reference tones keep working perfectly. Tuning by ear to a reference tone needs no microphone, no permission, and no data leaving your device. In fact, many teachers prefer that students learn reference tuning first, because it builds the ear that every other tuning method depends on.
If you do want microphone tuning and it is blocked, look for the microphone icon in your browser address bar and allow access for this site. Then press Start again. If your device has no microphone, the reference tones are your full tuning method, and they are a complete one: generations of guitarists tuned this way before electronic tuners existed.
Tuning Tips That Actually Help
Always tune up to the note, not down. If a string is sharp, loosen it below the target first, then tighten up to it. This keeps tension on the tuning peg and helps the string stay in tune. Stretch new strings gently by pulling them away from the fretboard and retuning several times. Check tuning after the first song, because playing and temperature changes move strings. And tune in the room where you will play, because a guitar tuned in a cold hallway will drift on a warm stage.
Frequently Asked Questions
Why does the reading jump around? Usually another string is ringing, or the note is dying away and harmonics take over. Mute other strings, play again, and read the number while the note is strong.
Is a few cents off acceptable? For practice, absolutely. For recording, aim as close to zero as your ear and patience allow, and check against the reference tones.
Does the tool record or upload my playing? No. Microphone audio is analyzed in your browser and never sent to a server.
Play a reference tone, match it by ear, check with the microphone, and play. Your guitar, and your ear, will thank you.