Virtual Piano
A playable keyboard with labelled keys, a choice of tone, sustain, and a readout of what you are playing — useful for checking a chord, humming a melody into pitch, or teaching a shape to someone over a call.
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Understand music theory by hearing it.
For learners, players and teachers: hear a chord, check its notes, then read why it works. Use playable examples, reference pages and practice tools without an account.
Search scales, chords, articles…/Every key has its own colour, wherever it turns up on this site. Pick one to open its guide.
Start here
Four articles in the order the ideas build: intervals, the major scale, chord function, and how phrases end.
- Reading Intervals at Sight: Generic and SpecificNaming an interval at sight takes two passes: count the staff positions first, then judge what the accidental does to the size.
- The Major Scale Formula: Whole and Half Steps ExplainedThe major scale is seven notes spaced whole, whole, half, whole, whole, whole, half. Here is the formula, four scales built from it, and the sharps and flats it forces.
- Functional Harmony: Tonic, Predominant, DominantTonic, predominant and dominant describe what a chord does to a phrase rather than what it is. This is how the three harmonic jobs divide the work.
- Cadences: How Phrases End in Tonal MusicAuthentic, half, plagal and deceptive cadences, and the real reason a close sounds strong: what happens in the bass, the top voice and the metre.
Check the notes, then hear them
Look up a scale, chord or key to see its spelling and formula. Play the notes to connect the written pattern with its sound.
Scales21 scale types, in every keyD Dorian · F♯ harmonic minor · B♭ bluesChords24 chord types, spelled and playableCmaj7 · G7♭9 · F♯m7♭5IntervalsFrom the minor second to the octaveRatios, cents and ear tipsKeysAll 24 major and minor keysSignature, chords, progressionsNote frequencies88 keys in Hz and MIDIA4 = 440 HzGlossaryTerms in plain languageFrom accidental to voice leading
Play, practise and plan
Check notes, build rhythms or calculate a recording setup. Everything runs in your browser, with no account or uploads.
Chord Finder
Select the keys you are holding and the tool names the chord, spells its notes and says which note is in the bass. Or start from a root and a quality and hear every inversion.
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Scale Finder
Pick a root and a scale type to see its spelled notes, its whole and half steps and the chords built on each degree. Or select the keys you have and find the scales that contain every one of them.
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Fretboard
Pick a tuning, a capo and a scale or chord, and the neck shows where every note lives. Click a dot to hear it, or play the scale or chord from its lowest root.
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Chord Progression Builder
Choose chords from any major or minor key, put up to sixteen in order and loop them on the audio clock. Roman numerals and chord names update together, so a progression written in one key can be heard and copied in any other.
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Circle of Fifths
Pick a key, read its signature, and hear the chords that belong to it — the diatonic triads, seventh chords and the standard progressions that hold a phrase together.
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Chord Transposer
Paste a chord chart, choose the new key, and every chord moves with it while the lyrics and the column alignment stay where they were. A capo helper shows which position gives the easiest open shapes.
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Chromatic Tuner
Sing, play or hum into the microphone and see the note, the frequency and how many cents sharp or flat you are — with a reference tone to tune against when the room is too noisy to listen.
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Metronome
A steady pulse you can trust: scheduled on the audio clock rather than by timers, with tap tempo, subdivisions, accent patterns and polyrhythms for the day you need to practise three against four.
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Tap Tempo
Tap along to a song or a practice track and read its tempo in beats per minute, with the spread of your taps, the length of each subdivision in milliseconds and a click pattern to check the result against the music.
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Rhythm Lab
Spread a number of pulses as evenly as possible over a cycle of steps, then play, rotate and edit up to three tracks of different lengths against each other. A practice tool for grooves, polyrhythms and beat ideas.
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Tone Generator
A pure tone at any frequency from 20 Hz to 20 kHz, with four waveforms, a note and cents readout, sweeps and a second tone for hearing beats. Useful for checking tuning, speakers and room resonances at a safe level.
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Ear Training
Three drills — intervals, chord qualities and scales — with the running score kept honest, references you can replay any time, and the answer drawn on the keyboard so the sound attaches to a shape.
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Room Mode Calculator
Estimate the low-frequency resonances of a rectangular room. Enter its dimensions, inspect the mode frequencies and export the list for comparison with measurements.
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Loop Tempo Calculator
Turn a trimmed loop length into BPM, then calculate the duration and playback ratio needed for a new tempo. Choose the beat unit explicitly, including dotted quarters in 6/8.
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String Tension Comparison
Estimate how the same string’s tension changes with tuning or scale length. Get a ratio without guessing its construction, or add a known reference tension for a force estimate.
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Audio File Size Calculator
Plan the storage for an uncompressed recording or a set of stems. Calculate audio bytes per file and in total, with sample-frame rounding and clear MB/MiB units.
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Twenty-four keys, worked out
Scale, key signature, seven chords and four progressions for every major and minor key. The colour of a key is its place on the circle of fifths: neighbours are close in colour because they are close in sound.
Harmony
Harmonizing a Melody: How to Choose the Chords
Harmonizing a melody means choosing a chord for each strong beat that contains the melody note. This worked example uses the opening of Ode to Joy in C.
Rhythm & Meter
Triplets and Tuplets Explained: Dividing the Beat in Three
A triplet fits three notes into the time of two of the same value. This article covers the ratio, the counts and how triplets differ from compound meter.
Fundamentals
Interval Inversion and Compound Intervals Explained
Inverting an interval moves its lower note up an octave, and the two numbers add to nine. Compound intervals are wider than an octave and take a simpler name.
Acoustics & Sound
Room Modes in a Small Studio: Calculate, Then Measure
Find a rectangular room’s first bass resonances, read the mode numbers and understand what a frequency list cannot tell you about your listening position.
Browse by topic
Thirteen areas, from the fundamentals of notation to jazz harmony, guitar and orchestration.
FundamentalsPitch, notation, intervals and scales — the vocabulary everything else on this site assumes.17 articlesHarmonyChord function, voice leading, cadence and modulation: how tonal music moves from one place to another.24 articlesRhythm & MeterBeats, subdivisions, time signatures, syncopation and hypermeter, and the difference between a cross-rhythm and a polyrhythm.10 articlesSongwriting & CompositionChord progressions, melody, song form and the practical decisions of writing music that holds together.3 articlesGuitar & FretboardTheory where guitarists actually use it: CAGED shapes, barre chords, positions, tunings, capos and tab.6 articlesJazz & Popular HarmonyExtensions, voicings, chord-scale theory and reharmonization: the grammar of jazz and modern popular harmony.3 articlesCounterpointLine against line — species, imitation, canon and fugue, and the rules that keep independent voices independent.6 articlesFormPhrases, periods and large-scale designs: how a piece of music tells you where you are.5 articlesTuning & TemperamentJust intonation, meantone, well temperament and equal temperament — and the cents that separate them.5 articlesAcoustics & SoundThe harmonic series, timbre, room resonances and digital recording: connect musical sound with physical and practical calculations.5 articlesOrchestrationRegisters, ranges, weight and voicing: writing for instruments as they actually behave.7 articlesEar Training & PracticeHow to hear, read and rehearse: ear training, transcription, sight-reading and practice that sticks.2 articlesMusic HistoryRepertoire, notation and practice from the medieval period to the present, told through the documents.7 articles
From a sound to an explanation
Use the site for a quick lookup or follow a reading path. You can try both before buying anything.
- Choose a question.
Start with intervals, search a chord such as Dm7, or open a tool for the task in front of you.
- Read, listen and compare.
Play an example or change the notes in a tool. Reference pages show the formulas behind the spelling.
- Follow the next idea.
Related articles and key guides connect a single example to harmony, rhythm and notation.
Do I need to pay or sign up?
Articles, reference pages and tools are free to use without an account. The optional ebooks and recording links lead to separate product or platform pages.
What if I am new to theory?
The interval guide is the first step in the four-article path above. Intro articles assume some music reading and an idea of what a scale is; the glossary helps with unfamiliar terms.
Will the tools work on my device?
Tools need JavaScript and a browser with Web Audio support. Press Play to enable sound. The tuner also needs microphone permission; see the tool directory for limits.
How can I check or correct an explanation?
Use the sources named in the articles and compare the playable examples. The colophon explains the review process; send a correction with the page and the source you checked.
The ebook
Music Theory: the site as a book
The site's working library as a structured ebook: intervals, keys, harmony, counterpoint, rhythm, form, tuning, orchestration and the history behind them.
- 78 pages
- PDF format
- $2.87
- By The musics.name project
The Gumroad link opens the seller’s listing and checkout. Review the current total and purchase terms there; the free site does not require a purchase.
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From the catalogue
Recordings released under their own artist names, on every platform they appear on.
