How to Identify Musical Intervals in 3 Easy Steps

Dr Rossella Rubini
Jul 31
2 min read

Understanding musical intervals is one of the most essential skills in music theory. Whether you are preparing for ABRSM Grade 1–5 online exams or taking Grades 6–8 paper exams, identifying intervals quickly and accurately will help you save time and score higher marks.

In this guide, you will learn a simple 3-step system to name any interval in seconds without getting confused by key signatures or complex scale counting.

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What is an Interval in Music?

A musical interval is the distance between two notes.

Exam Tip: Intervals are always measured using ordinal numbers (e.g., 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8ve). Never write standard cardinal numbers (1, 2, 3), or you will lose marks in written exam papers!

The 3-Step Method to Identify Any Interval

Follow these three steps to name every interval accurately:

Step 1: Identify the Number (Distance)

Count the number of letter names (or staff lines/spaces) from the bottom note to the top note, including the starting note.

Example: The distance from D to G includes D, E, F, and G. That is 4 steps, making it a 4th.

Step 2: Count the Tones and Semitones

Use a piano keyboard diagram (you can draw one on your exam scratch paper) to count the exact distance in semitones.

Example: D to E (1 tone) + E to F# (1 tone) + F# to G (1 semitone) = 2 ½ tones.

Step 3: Verify the Interval Type

Match the semitone count with standard interval rules to decide if it is Major, Minor, Perfect, Augmented, or Diminished:

Unisons, 4ths, 5ths, and Octaves can ONLY be Perfect (or Augmented/Diminished).

2nds, 3rds, 6ths, and 7ths can ONLY be Major (or Minor/Augmented/Diminished).

Quick Reference: Tones and Semitones Table

Use this quick guide to check the size of every major and perfect interval:

What Happens When Tones Don't Match?

If your interval has more or fewer semitones than the standard major or perfect distance, use these rules:

For Perfect Intervals (4th, 5th, 8ve):
- +1 semitone wider = Augmented
- -1 semitone narrower = Diminished
For Major Intervals (2nd, 3rd, 6th, 7th):
- +1 semitone wider = Augmented
- -1 semitone narrower = Minor
- -2 semitones narrower = Diminished

Take Your Exam Prep to the Next Level

Mastering intervals is the key to unlocking chords, harmony, and composition. If you want to build total confidence and pass your theory exams with distinction, explore our premium resources:

📝 Cheat Sheet (Intervals): Download the Cheat Sheet summarising this article and keep it with you when practising Theory. It's free!
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For a complete walkthrough on identifying intervals quickly, watch this tutorial video: How to Name Intervals Fast (For Beginners too). This video demonstrates the exact 3-step counting technique explained in the blog post on a real score.