Intervals with the same number can have different qualities. The quality changes by raising or lowering one of the notes by a half-step.

The following patterns apply to every key.

Seconds

Arrange the music alphabet in fourths:

B – E – A – D – G – C – F

The first two pairs (B-C and E-F) are naturally minor 2ⁿᵈs because they are only one half-step apart. The remaining pairs are naturally major 2ⁿᵈs.

Minor SecondsMajor SecondsMajor SecondsMajor SecondsMinor SecondsMinor Seconds
B-CB-C♯B♭-CA-BA-B♭A♯-B
E-FE-F♯E♭-FD-ED-E♭D♯-E
G-AG-A♭G♯-A
C-DC-D♭C♯-D
F-GF-G♭F♯-G

Rule

Minor 2ⁿᵈ → Major 2ⁿᵈ
• Raise the 2ⁿᵈ note one half-step.

Examples:
• B–C → B–C♯
• E–F → E–F♯

Major 2ⁿᵈ → Minor 2ⁿᵈ
• Lower the 2ⁿᵈ note one half-step.

Examples:
• A-B →  A-B♭
• D-E → D-E♭

Thirds

The same rule applies to thirds.

Minor ThirdsMajor ThirdsMajor ThirdsMajor ThirdsMinor ThirdsMinor Thirds
B-DB-D♯B♭-DG-BG-B♭G♯-B
E-GE-G♯E♭-GC-EC-E♭C♯-E
A-CA-C♯A♭-CF-AF-A♭F♯-A
D-FD-F♯D♭-F

Rule

Minor 3ʳᵈ → Major 3ʳᵈ

• Raise the 3ʳᵈ note one half-step.

Example:
• A-C → A-C♯

Major 3ʳᵈ → Minor 3ʳᵈ

• Lower the 3ʳᵈ note one half-step.

Example:
• C-E → C-E♭

Sixths

The same pattern also applies to sixths.

Minor SixthsMajor SixthsMajor SixthsMajor SixthsMinor SixthsMinor Sixths
B-GB-G♯B♭-GD-BD-B♭D♯-B
E-CE-C♯E♭-CG-EG-E♭G♯-E
A-FA-F♯A♭-FC-AC-A♭C♯-A
F-DF-D♭F♯-D

Rule

Minor 6ᵗʰ → Major 6ᵗʰ
• Raise the 6th note one half-step.

Example:
• A–F → A–F♯

Major 6ᵗʰ → Minor 6ᵗʰ
• Lower the 6ᵗʰ note one half-step.

Example:
• C–A → C–A♭

Sevenths

Again, the same rule applies.

Minor SeventhsMajor SeventhsMajor SeventhsMajor SeventhsMinor SeventhsMinor Sevenths
B-AB-A♯B♭-AC-BC-B♭C♯-B
E-DE-D♯E♭-DF-EF-E♭F♯-E
A-GA-G♯A♭-G
D-CD-C♯D♭-C
G-FG-F♯G♭-F

Rule

Minor 7ᵗʰ → Major 7ᵗʰ
• Raise the 7ᵗʰ note one half-step.

Example:
• A–G → A–G♯

Major 7ᵗʰ → Minor 7ᵗʰ
• Lower the 7ᵗʰ note one half-step.

Example:
• C–B → C–B♭

Fourths

Unlike seconds, thirds, sixths, and sevenths, fourths are perfect intervals.

Perfect FourthsDim. FourthsAug. FourthsPerfect FourthsAug. Fourths
B-EB-E♭B-E♯F-B♭F-B
E-AE-A♭E-A♯F♯-B
A-DA-D♭A-D♯
D-GD-G♭D-G♯
G-CG-C♭G-C♯
C-FC-F♭C-F♯

Rule

Perfect 4ᵗʰ → Diminished 4ᵗʰ
• Lower the 4ᵗʰ note one half-step.

Example:
• C–F → C–F♭

Perfect 4ᵗʰ → Augmented 4ᵗʰ
• Raise the 4ᵗʰ note one half-step.

Example:
• C–F → C–F♯

Fifths

The same applies to fifths:

Perfect FifthsDim. FifthsAug. FifthsDim. FifthPerfect Fifth
E-BE-B♭E-B♯B-FB-F#
A-EA-E♭A-E♯
D-AD-A♭D-A♯
G-DG-D♭G-D♯
C-GC-G♭C-G♯
F-CF-C♭F-C♯

Rule

Perfect 5ᵗʰ → Diminished 5ᵗʰ
• Lower the 5ᵗʰ note one half-step.

Perfect 5ᵗʰ → Augmented 5ᵗʰ
• Sharp the 2ⁿᵈ note

Example:
• C–G → C–G♭

Perfect 5ᵗʰ → Augmented 5ᵗʰ
• Raise the 5ᵗʰ note one half-step.

Example:
• C–G → C–G♯

Narrowed by one half-step←Original Interval→Widened by one half-step
MinorMajorAugmented
DiminishedMinorMajor
DiminishedPerfectAugmented

Summary

Rather than memorizing every interval, remember the pattern:

Major ↔ Minor

  • Raise the 2ⁿᵈ note = Minor → Major
  • Lower the 2ⁿᵈ note = Major → Minor

Perfect ↔ Diminished / Augmented

  •  Lower the 2ⁿᵈ note = Perfect → Diminished
  • Raise the 2ⁿᵈ note = Perfect → Augmented