Definition of Third:

A third is an interval equal to three scale degrees that is most commonly major or minor*:

  • Major Third (M3)
    Equal to four half steps; the distance between GB is a major third.
  • Minor Third (m3)
    Equal to three half steps; GB♭


*By itself, the word "third" often refers to the major third (it’s common to omit the word ‘major’ when speaking of intervals, chords, and keys.


The Third as a Scale Degree

This refers to the third note or chord in a musical scale.

When reading or playing a scale, the third note will be the first clue as to whether that scale is major or minor. Compare the following G scales:

  • G Major:  G - A - B - C - D - E - F♯
  • G Minor:  G - A - B♭ - C - D - E - F


 ►  View G Major’s Key Signature
 ►  View G Minor’s Key Signature


The Role of the Third in Chords

In many chord types, the third is an important building block. For example, major and minor chords are built similarly, except for their thirds:


See root note.


Also Known As:

  • terza [maggiore / minore]  (It)
  • tierce [majeure / mineure]  (Fr)
  • Terz [grosse Terz / kleine Terz]  (Ger)


More Musical Intervals:

Musical Symbols:
■ Staff & Barlines
■ The Grand Staff
■ Key Signatures
■ Time Signatures

■ Note Lengths
■ Dotted Notes
■ Music Rests
■ Tempo Commands

■ Accidentals
■ Articulation
■ Dynamics & Volume
■ 8va & Octave Commands

■ Repeat Signs
■ Segno & Coda Signs
■ Pedal Marks
■ Piano Chords

■ Trills
■ Turns
■ Tremolos
■ Glissando
■ Mordents


Beginner Piano Lessons
 ▪  Notes of the Piano Keys
 ▪  The Point Of Double-Sharps
 ▪  Finding Middle C on the Piano
 ▪  Essential Piano Fingering
 ▪  Comparing Major & Minor Chords

Getting Started on Keyboards
 ▪  Sitting Correctly at the Keys
 ▪  Playing Piano vs. Electric Keyboard
 ▪  How to Buy a Used Piano

Piano Chords
 ▪  Chord Types & Symbols in Sheet Music
 ▪  Root Notes & Chord Inversion
 ▪  Diminished Chords & Dissonance
 ▪  Essential Piano Chord Fingering

Piano Care
 ▪  Everyday Piano Care
 ▪  Safely Whiten Your Piano Keys
 ▪  When to Tune a Piano
 ▪  Piano Room Temps & Humidity Levels

Piano Recitals & Performing
 ▪  What to Eat & Drink Before a Performance
 ▪  Concert Etiquette for the Audience
 ▪  Warming Up for a Piano Performance
 ▪  Overcoming Mistakes On Stage

♫ Musical Quizzes!
 ● Identify the Piano Keys
 ● Key Signature Quiz
 ● Note Length & Rest Quiz (U.S. or U.K. English)
 ● Grand Staff Notes Quiz
 ● Time Signature & Rhythm Quiz

Reading Piano Music
• Note-Lengths in U.K. & U.S. English
• Notes of the Piano Keys
• Memorize the Grand Staff Notes
• Reading Music Rests

Piano Chords
• Easy Bass Piano Chords
• Chord Types & Symbols
• Piano Chord Fingering
• Diminished Chords & Dissonance

Reading Musical Symbols
• Note Accents & Articulation Marks
• How to Play Dotted Notes
• Accidentals & Double-Accidentals
• Reading Segno & Coda Repeats

Beginner Piano Lessons
• Comparing Major & Minor
• Understanding the Key Signature
• Types of Barlines
• BPM & Tempo Commands
• Left Hand Piano Fingering


Helpful Info For Owning a Piano
How to Safely Whiten Your Piano Keys
Learn ivory-safe methods for brightening up your acoustic piano keys, and find out what you can do to prevent keyboard yellowing.

When to Tune a Piano
Find out when (and how frequently) you should schedule a professional piano tuning to keep your piano healthy and on-pitch.

Easy-to-Spot Signs of Piano Damage
Before you buy or sell an acoustic piano, learn how to assess it for both internal and external damage.

Ideal Piano Temp & Humidity Levels
Learn how to maintain sound quality and piano health by monitoring the temperature, humidity, and natural light in your piano room.


Illustrated Piano Chords:
AbmajAbma7Abma9  |  AbminAbm7Abm9  |  AbdimAb°7  |  AbaugAb+7  |  Absus2Absus4