Mandolin Tuner

Online Mandolin Tuner: The Complete Guide

A mandolin doesn't have four strings — it has eight, arranged in four pairs called courses, with both strings in a pair tuned to the same note. Getting all eight in tune with each other, not just close to the right pitch, is what gives a mandolin its signature shimmering, chorused tone. This online tuner runs in your browser, listens through your device's microphone, and shows exactly how close each course is to being in tune, in real time.

How does an online mandolin tuner work?

This tuner uses the Web Audio API built into modern browsers to capture a short sample of sound from your microphone, then runs it through an autocorrelation algorithm. Autocorrelation compares a sound wave against slightly delayed copies of itself to find the point where the pattern repeats — that repeat rate is the fundamental frequency of the note being played. Once the frequency is known, it's compared against the nearest standard pitch (like A4 at 440.00 Hz) to calculate how many cents sharp or flat the string is.

How to Tune a Mandolin Online, Step by Step

1. Find a quiet space. Because each course has two strings that need to match each other exactly, background noise makes it harder to hear subtle differences between them.
2. Tap "Start Tuner" and allow microphone access when your browser asks. This permission is required for any pitch-detection tuner to hear your strings.
3. Mute one string in each pair with a finger or pick while tuning the other, so the tuner reads a single clean pitch rather than two slightly different frequencies at once.
4. Watch the needle and note name. The tuner automatically detects which course you're closest to and highlights it below the gauge.
5. Turn the tuning peg slowly. If the reading shows a flat cents value, tighten the string; if it shows sharp, loosen it slightly, then re-pluck to check.
6. Repeat for the second string in that course, matching it to the first, then move on to the next course.

Standard Mandolin Tuning Notes (GDAE)

A standard 8-string mandolin is tuned in fifths, using the exact same note relationships as a violin: G, D, A, and E. Each of the four courses below represents two strings tuned to the same pitch:

Why Paired Courses Make Tuning Different

On a guitar, each string is its own independent pitch. On a mandolin, four of the "notes" you hear are actually two strings vibrating together, and any tiny mismatch between them creates an audible chorusing or beating effect rather than a clean single tone. A course that's technically "close enough" on average can still sound noticeably out of tune if the two strings inside it disagree by even a few cents. This is why mandolin players typically tune one string in a course, mute it, tune the second string to match, then release both and check the pair together.

Because this tuner detects pitch chromatically, it works equally well whether you're tuning a full course, an isolated single string within a course, or checking the two strings against each other one at a time.

Common Mandolin Tuning Problems (and How to Fix Them)

The tuner won't detect any sound

This almost always comes down to one of three things: microphone permission was denied, the page isn't loaded over a secure (https) connection, or your input volume is too low. Check your browser's site settings to confirm microphone access is allowed, and make sure no other tab or app is already using the microphone.

A course still sounds "off" even though the tuner reads in tune

This usually means the two strings within that course are tuned to slightly different pitches that happen to average out near the correct note. Isolate and tune each string in the course individually rather than only checking the pair together.

Strings won't hold their tuning

New strings stretch during their first few days of use and will drift flat repeatedly until they settle — this is normal and not a sign of a broken instrument. Mandolins are also sensitive to humidity and temperature changes, which can shift tuning noticeably between sessions.

Alternate Mandolin Tunings

Because this tuner detects pitch chromatically rather than only listening for four fixed notes, it also works for common alternate and related tunings:

• Cross-tuning (Open D): A3, D4, A4, D5 — used in some old-time and fiddle-tune styles for open drone strings.
• Mandola tuning: C3, G3, D4, A4 — a fifth lower than standard mandolin, used on the larger mandola.
• Octave mandolin tuning: G2, D3, A3, E4 — an octave below standard mandolin on a longer-scale instrument.

For any of these, simply read the note name shown on the tuner as you adjust each course, rather than relying on the four preset buttons built for standard GDAE tuning.

Frequently Asked Questions

Pitch detection runs entirely on your device — audio from your microphone is never recorded, stored, or sent to a server.