Borrowed Chord Identifier

Select a chord root, type, and your key to instantly identify whether the chord is diatonic or borrowed — and which parallel mode or scale it comes from.

Created by Luis GonzalezLast updated: May 9, 2026

How to Use This Calculator

1
Select the Chord Root Note
Choose the root note of the chord you want to analyze (e.g., C, D, E, F, G, A, or B).
2
Select the Chord Type
Choose the quality of the chord: Major, Minor, Diminished, Augmented, or Dominant 7th.
3
Select the Key Root Note
Choose the root note of the key your piece is in (e.g., C for C major or C minor).
4
Select the Key Mode
Choose Major or Minor (Natural) to specify the mode of the key.
5
Review your results
The calculator displays six cards: Diatonic Chord, Scale Degree, Borrowed From, Harmonic Tension, Tonal Color Effect, and Resolution Tendency.

Example Calculation

A composer analyzes a C Major chord in the key of C Major to determine whether it is diatonic or borrowed.

Chord Root Note

Chord Type

Major

Key Root Note

Key Mode

Major

Results

Diatonic Chord

C Major, Scale Degree: I, Borrowed From: Not borrowed, Harmonic Tension: Low, Tonal Color Effect: Neutral — matches key colour, Resolution Tendency: Functions within C Major harmony

Tips

Mastering Diatonic Harmony First

Before identifying borrowed chords, ensure a strong grasp of diatonic chords for all major and minor keys. For instance, in C major, the diatonic triads are C, Dm, Em, F, G, Am, Bdim.

Common Borrowed Chords

Some of the most common borrowed chords include the bVI (e.g., Ab in C major) and bIII (e.g., Eb in C major) from the parallel minor, often used to add color or tension.

Context is Key

A chord might be technically diatonic but function as a temporary tonicization, which is distinct from a borrowed chord. Always consider the surrounding harmonic progression; a chord must clearly deviate from the established key's scale to be considered borrowed.

Understanding Mode Mixture in Music Composition

The Borrowed Chord Identifier helps musicians and composers analyze harmonic progressions by determining if a given chord is diatonic to the current key or borrowed from its parallel mode. This distinction is crucial for understanding harmonic function and color, particularly when encountering chords that deviate from the expected scale. In popular music, borrowed chords are common, with roughly 15-20% of non-diatonic chords in a typical song being mode mixture, adding richness and complexity.

The Logic Behind Identifying Borrowed Chords

The core logic of the Borrowed Chord Identifier hinges on a simple comparison: is the chord part of the established key's natural scale, or does it originate from its parallel major or minor counterpart? If a piece is in C major, for example, a G major chord is diatonic. However, an Ab major chord is not; it's typically borrowed from C minor. The calculator’s primary function is to categorize a chord based on whether it fits the diatonic criteria or indicates a mode mixture.

The calculation logic is straightforward:

result = isDiatonic === 1 ? 'Diatonic chord' : 'Borrowed from parallel ' + (parallelMode === 1 ? 'major' : 'minor')

Here, isDiatonic is 1 for a diatonic chord and 0 for a borrowed one. parallelMode specifies the source mode (1 for major, 2 for minor) if the chord is borrowed. This simple conditional statement allows for clear classification.

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Analyzing a Chord in C Major

Imagine a composer is working on a piece in C major and wants to analyze a particular chord. They encounter an A-flat major chord (Ab-C-Eb). In C major, the diatonic chords are C major, D minor, E minor, F major, G major, A minor, and B diminished. The A-flat major chord is not among these.

Is Chord Diatonic? The A-flat major chord is not diatonic to C major. So, the input is 0.
Parallel Mode? Since the chord is not diatonic, we consider which parallel mode it might be borrowed from. C minor is the parallel minor of C major. In C minor, the VI chord is A-flat major. Therefore, the chord is borrowed from the parallel minor. The input is 2.

The Borrowed Chord Identifier would output "Borrowed from parallel minor," accurately classifying the A-flat major chord in the context of C major. This helps the composer understand the harmonic color and origin of the chord.

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Musical Application Context

Borrowed chords are a fundamental tool in composition and arrangement, enabling musicians to introduce harmonic variety and emotional depth without fully modulating to a new key. In composition, they are often used to create moments of tension, resolution, or unexpected color. For instance, borrowing a bVI chord (e.g., Ab major in C major) from the parallel minor can evoke a melancholic or dramatic feeling, a common technique in film scores and pop ballads. Arrangers frequently employ borrowed chords to thicken textures or create richer voicings, transforming a simple diatonic progression into something more sophisticated. In jazz, mode mixture is pervasive, with musicians regularly drawing from various parallel modes to extend harmonic possibilities and improvise over complex changes, creating a vibrant and ever-evolving soundscape.

Variants of this formula and when to use them

While the core concept of identifying a borrowed chord remains consistent, the "formula" (or rather, the classification logic) can have nuanced variants depending on the specific harmonic analysis framework being applied. The calculator primarily uses a binary "diatonic vs. borrowed" classification based on the parallel major/minor. However, advanced analysis might distinguish between different types of mode mixture or even temporary tonicizations that appear similar to borrowed chords.

One key variant involves explicitly categorizing the degree of the borrowed chord. For example, instead of just "Borrowed from parallel minor," an extended analysis might specify "bVI from parallel minor" or "bIII from parallel minor." This requires an additional step where the user identifies the Roman numeral function of the non-diatonic chord within the parallel mode.

Basic Classification (as used by this calculator):

ChordStatus = IsDiatonic ? "Diatonic" : "Borrowed from Parallel Mode"

This is ideal for quick identification and for students learning the foundational concept of mode mixture.

Extended Classification (manual or with additional inputs):

ChordStatus = IsDiatonic ? "Diatonic" : "Borrowed " + RomanNumeral + " from Parallel Mode"

This variant provides more detailed information, useful for in-depth harmonic analysis in academic settings or for composers meticulously documenting their harmonic choices. The primary difference lies in the level of detail provided about the borrowed chord's function within its source mode, requiring the user to identify the Roman numeral designation.

Frequently Asked Questions

What is a borrowed chord in music theory?

A borrowed chord, also known as a mode mixture chord, is a chord taken from a parallel key (e.g., C minor when the current key is C major) and used in the current key. It adds harmonic color and often a sense of tension or drama without fully modulating.

How can I tell if a chord is borrowed from a parallel minor?

To identify a chord borrowed from a parallel minor, first determine if the chord's root or quality is outside the current major key's diatonic harmony. If it aligns with a chord from the parallel minor key (e.g., using an Eb major chord in C major, which is the III chord in C minor), it's likely borrowed.

Why do composers use borrowed chords?

Composers use borrowed chords primarily to introduce harmonic variety, add emotional depth, or create specific expressive effects. They can provide a darker, more melancholic feel when borrowing from minor into major, or a brighter, more resolute sound when borrowing from major into minor, enriching the harmonic palette.

Can a chord be borrowed from a parallel major into a minor key?

Yes, chords can also be borrowed from a parallel major into a minor key. For instance, in C minor, a composer might use an F major chord (IV in C major) instead of the diatonic F minor (iv in C minor) to create a brighter or more uplifting sound. This technique is less common but equally valid.