Last updated: March 2026
What Is the Online Guitar Tuner?
The Online Guitar Tuner is a free browser-based tool that detects the pitch of your guitar strings through your microphone and shows whether each string is sharp, flat, or perfectly in tune. No signup, no app download, no ads -- just open the page and start tuning.
There are over 50 million guitar players in the United States alone, and every one of them needs to tune before playing. Dedicated clip-on tuners cost $15-30, and tuner apps require installing software that often shows ads or nags for upgrades. This browser-based tuner uses autocorrelation pitch detection, the same algorithm found in professional hardware tuners, running entirely through your device's microphone.
The tuner includes 12+ preset tunings covering Standard, Drop D, Drop C, DADGAD, Open G, Open D, and Half Step Down for guitar, plus standard and drop tunings for bass and ukulele. A chromatic mode detects any note on any pitched instrument. Each string button plays a reference tone so you can tune by ear if you prefer.
How to Use the Online Guitar Tuner
- Click Start Tuner and allow microphone access when your browser asks.
- Select your instrument (guitar, bass, ukulele) and tuning preset, or choose Chromatic for any instrument.
- Pluck a single string. The tuner detects the note and shows it on the gauge.
- If the needle is left of center, the string is flat (too low) -- tighten it.
- If the needle is right of center, the string is sharp (too high) -- loosen it.
- When the needle is centered and the indicator turns green, the string is in tune.
Key Features
Real-time needle gauge. A smooth, animated needle shows exactly how far sharp or flat you are in cents. Green means in tune, yellow means close, red means keep adjusting.
12+ tuning presets. Standard, Drop D, Drop C, DADGAD, Open G, Open D, Half Step Down for guitar. Standard and Drop D for bass. Standard and Low G for ukulele. Switch tunings with a single tap.
Reference tones. Tap any string button to hear a pure sine wave at that note's exact frequency. Useful for training your ear or tuning in a noisy environment where the microphone struggles.
Adjustable A4 reference. Set A4 from 430 to 450 Hz to match orchestral or ensemble tuning standards. All note frequencies recalculate automatically.
Frequently Asked Questions
How accurate is an online guitar tuner?
This tuner uses autocorrelation pitch detection, the same algorithm in professional hardware tuners. It is accurate to within ±1 cent when used in a quiet room with a clear signal. For best results, pluck one string at a time and let it ring.
What is standard guitar tuning?
Standard guitar tuning from lowest (thickest) to highest (thinnest) string is E2, A2, D3, G3, B3, E4. This is often written as EADGBE. Each string is tuned roughly a perfect fourth apart, except for the interval between G3 and B3 which is a major third.
Can I tune my guitar with my phone?
Yes. This tuner works on iPhone (Safari) and Android (Chrome). Tap Start Tuner to activate your phone’s microphone. Hold your phone near the guitar for best results. Make sure your browser has microphone permission enabled in your device settings.
What is Drop D tuning?
Drop D lowers the 6th string from E2 to D2 while keeping all other strings standard (D-A-D-G-B-E). It is popular in rock and metal because it allows you to play power chords with a single finger across the bottom three strings.
Why does the tuner show the wrong note?
Make sure you are plucking only one string at a time and muting the others. Background noise, multiple strings ringing, or harmonics can confuse the pitch detector. Move to a quieter room and pluck the string closer to the bridge for a cleaner fundamental tone.