Chord Finder - Identify and Name Chords

A chord finder is a music-theory tool that names the chord you are playing or hearing from the notes it contains. Pick up to five pitch classes from the dropdowns, optionally lock the root, and the tool returns the most likely chord symbol plus up to five alternates ranked by how well their pitch-class set matches the input.

• • Identify a chord you hear: Select the notes you hear on guitar, piano, or any instrument to find the chord symbol in seconds.
• • Name an unfamiliar chord from sheet music: Read the notes from a lead sheet that uses noteheads instead of symbols and translate them into Cmaj7, Fm7b5, or similar.
• • Disambiguate similar chords by adding notes: Add a fourth note to distinguish a major triad from a major 7th, a dominant 7th, or a 6th chord.
• • Pick a root when the bass note is unclear: Leave the optional root on 'Any' and let the tool rank every possible root by how well the chord it builds matches your input notes.

Adding a fourth or fifth note is the most reliable way to break a tie, because a three-note triad can describe both a major and a minor chord with a different bass note (for example C-E-G is both a C major triad in root position and an A minor triad in first inversion), and the alternates list surfaces that ambiguity for you.

Once you know the chord symbol, the Chord Calculator takes the root and quality and returns the notes, the scale-degree formula, and the standard chord symbol in the same enharmonic spelling.

The tool reduces every entered note to a pitch class using mod-12 arithmetic, then scores every (root, quality) candidate by how well its pitch-class set covers the input.

• note1..note5: Up to 5 pitch classes from the dropdowns; 'None' skips a slot. Enharmonic spellings such as C# and Db collapse to one pitch class before scoring.
• rootFilter: Optional root selector; 'Any' tries all 12 roots, otherwise candidates are restricted to the chosen root.
• chordTable[type]: Lookup of semitone intervals for the 14 supported qualities (major, minor, augmented, diminished, sus2, sus4, dominant 7, major 7, minor 7, minor-major 7, diminished 7, half-diminished 7, major 6, minor 6).
• score: Rank value where 1000 is exact, 500 means chord extends input, 200 means input extends chord, partial falls off from 50 per matched note.

This tool reuses the same 14-quality interval table that drives the chord calculator, which means every chord it names is exactly the chord the calculator can build in reverse. When the input has fewer than three unique pitch classes the tool falls back to an empty-state message instead of inventing a match, because chord identity by definition requires at least three notes.

According to Wikipedia - Pitch class, octave-equivalent pitches share a single pitch class computed by reducing the MIDI note number modulo 12, which is exactly the operation this tool runs on every input before scoring candidates.

According to Wikipedia - Set theory (music), two chords are equivalent when they share the same pitch-class set regardless of voicing or octave, which is exactly the comparison this tool runs when it ranks candidates by how well their pitch-class set matches the user-entered notes.

Reducing a note name to a pitch class is the same mod-12 operation the Modulo Calculator performs on any positive integer.

Four ideas from pitch-class set theory explain how a handful of note names turn into a single ranked chord symbol.

These four ideas let the tool behave like a deterministic search algorithm rather than a fuzzy guess: every candidate has a numeric score and the top six are returned in order.

Once the chord is named, the Chord Transposer shifts that chord (and any progression it belongs to) into a new key while keeping the same chord quality and the same slash-bass note.

Five short steps take you from a handful of heard notes to a ranked list of chord names without touching a chord dictionary.

1. 1 Pick the notes you hear: Set each dropdown to a pitch class in the chord, or leave it on 'None' to skip a slot; order does not matter.
2. 2 Set an optional root note: If you know the bass note or song key, lock the optional root; otherwise leave it on 'Any' to let the tool try all 12 roots.
3. 3 Read the primary chord symbol: The first result row shows the most likely chord symbol such as C, F#m7, or Bbdim7 based on the highest match score.
4. 4 Check the match type: The match type tells you whether the tool found an exact match, whether the matched chord adds notes you did not enter, or whether only a partial overlap was found.
5. 5 Scan the alternates list: The 'Could also be' row lists up to five other chords whose pitch-class sets also fit the notes, useful for spotting inversions and slash chords.

A guitarist hears four notes ringing out after strumming an open C-shape barre chord and wants to confirm whether it is a C major triad or a Cmaj7. They pick C, E, G, B from the dropdowns and leave the optional root on 'Any'. The tool returns Cmaj7 as the exact match and lists C (major triad) as the first alternate so they can decide whether to call the chord C or Cmaj7 depending on the song.

Walking from the root to each chord tone in semitone steps is the same fixed-increment pattern the Arithmetic Sequence Calculator builds from any starting term and common difference.

Four practical reasons the tool is faster than paging through a chord dictionary or working intervals out by ear.

• • Fast note-to-symbol translation: Pick up to five notes and the tool returns the most likely chord plus five alternates in one step, which is faster than searching a chord book for each possible name.
• • Removes enharmonic ambiguity: C# and Db collapse into the same pitch class before scoring, so users who mix sharp and flat spellings still get a single ranked answer instead of two competing lists.
• • Shares the 14-quality table with the chord calculator: Because both tools share the same interval table, you can move from naming a chord to building its notes (or vice versa) without learning a second set of rules.
• • Tells you when the input is incomplete: An explicit empty-state message appears when fewer than three unique notes are entered, so you know to add a note instead of trusting a guess based on two pitches.

The tool is a music-theory reference, not an ear-training app. It will name any chord you enter, but it cannot tell whether the listener can hear the difference between a major 7th and a dominant 7th on their own.

The semitone intervals behind chord notes follow the same proportional logic the Ratio Calculator simplifies, since both tools walk a known start to a known end through integer pairs.

Three practical variables change the ranked result and two approximation caveats explain why the tool is a reference rather than a substitute for listening.

• • The tool covers the 14 most common tonal-music chord qualities and does not include extended harmony like 9th, 11th, or 13th chords, altered dominants beyond the basic b9, or nontertian harmony such as quartal or quintal voicings.
• • Scoring is purely set-based, so the tool cannot tell a chord from an arpeggio with the same notes over time, and does not represent microtonal intervals, just intonation, or non-Western tunings.

These caveats matter most when the input set is short, because a two-note input is intentionally rejected since chord identity requires at least three notes by definition.

According to Wikipedia - Chord (music), a chord is a set of multiple notes played together whose identity is set by the root and the intervals above it, which is the same rule this tool uses to rank candidates by pitch-class set match.

Enharmonic equivalence between C# and Db chords is the same equality the Equivalent Ratio tool handles between different representations of the same value.