Understanding Diatonic Chord Progressions
This tool builds a chord progression the way traditional music theory does: it starts from a major or natural minor scale, stacks thirds on top of each scale degree to form a chord, and reads off the result as both a letter-named chord and a roman numeral. Enter a key, a scale, a progression pattern (a sequence of scale degrees like 1-5-6-4), and a chord type, and the calculator returns the actual chords for that progression.
The formula
A major scale follows the interval pattern whole-whole-half-whole-whole-whole-half (in semitones from the root: 0, 2, 4, 5, 7, 9, 11). A natural minor scale follows whole-half-whole-whole-half-whole-whole (0, 2, 3, 5, 7, 8, 10). Once the seven scale notes are known, each diatonic chord is built by stacking every other note starting on a given scale degree — the 1st, 3rd, and 5th notes counted from that degree for a triad, plus the 7th note for a four-note seventh chord.
- Major scale triads: I, ii, iii, IV, V, vi, vii° — major, minor, minor, major, major, minor, diminished.
- Natural minor triads: i, ii°, III, iv, v, VI, VII — minor, diminished, major, minor, minor, major, major.
- Roman numeral case encodes chord quality: uppercase numerals are major (or dominant) chords, lowercase are minor, and a degree mark (°) denotes diminished.
Reading a progression
A progression pattern like 1-5-6-4 means "play the chord on the 1st scale degree, then the 5th, then the 6th, then the 4th." In C major that resolves to C, G, Am, F — one of the most recorded chord sequences in popular music. The same 1-5-6-4 pattern in A natural minor instead produces Am, Em, F, Dm, because the underlying scale — and therefore each chord's quality — changes.
Assumptions
The calculator assumes standard 12-tone equal temperament, strictly diatonic harmony (no borrowed chords, secondary dominants, or chromatic alterations), and spells every note using sharps rather than key-specific enharmonic spelling (so it shows D# rather than Eb). These are simplifications that keep the math transparent; a full arrangement may use different spellings or add chords borrowed from outside the scale.
Frequently Asked Questions
How does the calculator turn scale degrees into actual chords?
What do the roman numerals like ii, V, and vii° mean?
Why do the same scale-degree numbers produce different chords in major versus minor?
Does this include 7th chords, borrowed chords, or other extensions?
Common Tip Percentages
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|---|---|---|
| Restaurant (sit-down) | 15–20% | 20%+ for exceptional service |
| Food delivery | 10–20% | Consider extra for long distances |
| Taxi / rideshare | 10–20% | More for assistance with luggage |
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| Category | % of Net Income | Examples |
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| Needs | 50% | Rent, groceries, utilities, insurance |
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| Savings / Debt | 20% | Emergency fund, retirement, extra payments |
Common Measurement Conversions for Everyday Use
| Quantity | US / Imperial | Metric Equivalent |
|---|---|---|
| 1 cup | 8 fl oz | 237 mL |
| 1 pint | 16 fl oz | 473 mL |
| 1 quart | 32 fl oz | 946 mL |
| 1 gallon | 128 fl oz | 3.785 L |
| 1 lb | 16 oz | 453.6 g |
| 1 ft | 12 in | 30.48 cm |