Interval Size and Quality Calculator

Understanding interval size and quality is fundamental to music theory. This calculator helps you determine the size and quality of an interval between two musical notes, providing both the numerical size and the musical quality (perfect, major, minor, etc.).

What is an Interval?

In music theory, an interval is the distance between two pitches. It's defined by both the number of scale degrees between the notes and the quality of that distance. For example, the interval between C and E is a "major third" because it spans three scale degrees (C, D, E) and has a major quality.

Intervals are the building blocks of harmony and melody. Understanding them helps you compose better music and analyze existing pieces.

Interval Size

The size of an interval is determined by counting the number of scale degrees between the two notes. For example:

C to D is a second (2)
C to E is a third (3)
C to G is a fifth (5)
C to A is a sixth (6)

Formula: Interval Size = |Note2 - Note1|

Where Note1 and Note2 are the positions of the notes on the chromatic scale (C=1, C#=2, D=3, etc.).

Interval Quality

The quality of an interval describes whether it's perfect, major, minor, augmented, or diminished. This is determined by the specific notes being used:

Perfect intervals: 1st, 4th, 5th, 8th
Major intervals: 2nd, 3rd, 6th, 7th
Minor intervals: 2nd, 3rd, 6th, 7th
Augmented intervals: any interval that's a semitone larger than its major form
Diminished intervals: any interval that's a semitone smaller than its minor form

Remember that the quality of an interval depends on the specific notes being used, not just the size. For example, C to D is a minor second, but C to D# is a major second.

How to Use the Calculator

Select the first note from the dropdown menu
Select the second note from the dropdown menu
Click the "Calculate" button
View the results showing both the interval size and quality

The calculator will display the interval size (number of scale degrees) and the interval quality (perfect, major, minor, etc.).

Examples

Example 1: C to E

C to E is a major third because:

Size: 3 (C, D, E)
Quality: Major (E is a major third above C)

Example 2: E to G#

E to G# is an augmented fourth because:

Size: 4 (E, F, G, A)
Quality: Augmented (G# is a semitone larger than the perfect fourth G)

FAQ

What is the difference between interval size and quality?

Interval size refers to the number of scale degrees between two notes (e.g., second, third, etc.). Interval quality describes whether the interval is perfect, major, minor, augmented, or diminished.

How do I determine the quality of an interval?

The quality of an interval is determined by the specific notes being used. For example, C to D is a minor second, but C to D# is a major second.

What is the difference between a major and a perfect interval?

A perfect interval is exactly the size it should be (e.g., a perfect fifth is exactly 7 semitones). A major interval is slightly larger than it should be (e.g., a major third is 4 semitones, which is a semitone larger than a minor third).