Common metre or common measure^[1]—abbreviated as C. M. or CM—is a poetic metre consisting of four lines that alternate between iambic tetrameter (four metrical feet per line) and iambic trimeter (three metrical feet per line), with each foot consisting of an unstressed syllable followed by a stressed syllable. The metre is denoted by the syllable count of each line, i.e. 8.6.8.6, 86.86, or 86 86, depending on style, or by its shorthand abbreviation "CM".

Common metre has been used for ballads such as "Tam Lin" and hymns such as "Amazing Grace" and the Christmas carol "O Little Town of Bethlehem". The upshot of this commonality is that lyrics of one song can be sung to the tune of another; for example, "Advance Australia Fair", "House of the Rising Sun", Pokémon Theme and "Amazing Grace" can have their lyrics set to the tune of any of the others. Historically, lyrics were not always wedded to tunes and would therefore be sung to any fitting melody; "Amazing Grace", for instance, was not set to the tune "New Britain" (with which it is most commonly associated today) until fifty-six years after its initial publication in 1779.

Common metre is related to other poetic forms.

Like common metre, ballad metre comprises couplets of tetrameter (four feet) and trimeter (three feet). However, the feet need not be iambs (with one unstressed and one stressed syllable): the number of unstressed syllables is variable.^[2] Ballad metre is "less regular and more conversational"^[2] than common metre.

In each stanza, ballad form typically needs to rhyme only the second lines of the couplets, not the first, giving a rhyme scheme of ABCB, while common metre typically rhymes both the first lines and the second lines, ABAB.^{[citation needed]} A ballad in groups of four lines with a rhyme scheme of ABCB is known as the ballad stanza.

He does not rise in piteous haste
   To put on convict-clothes,
While some coarse-mouthed Doctor gloats, and notes
   Each new and nerve-twitched pose,
Fingering a watch whose little ticks
   Are like horrible hammer-blows.

— Oscar Wilde, from The Ballad of Reading Gaol

The fourteener is a metrical line of 14 syllables (usually seven iambic feet).^[3]

Fourteeners typically occur in couplets. Fourteener couplets broken into quatrains (four-line stanzas) are equivalent to quatrains in common metre or ballad metre:^[3] instead of alternating lines of tetrameter and trimeter, a fourteener joins the tetrameter and trimeter lines to give seven feet per line.^[4]

The fourteener gives the poet greater flexibility than common metre, in that its long lines invite the use of variably placed caesuras and spondees to achieve metrical variety, in place of a fixed pattern of iambs and line breaks.^{[citation needed]}

Whose sense in so evil consort, their stepdame Nature lays,
That ravishing delight in them most sweet tunes do not raise;
Or if they do delight therein, yet are so cloyed with wit,
As with sententious lips to set a title vain on it:
O let them hear these sacred tunes, and learn in wonder’s schools,
To be (in things past bounds of wit) fools, if they be not fools.

— Philip Sidney, from Astrophel and Stella (Seventh Song)

Another common adaptation of the common metre is the common-metre double, which as the name suggests, is the common metre repeated twice in each stanza, or 8.6.8.6.8.6.8.6. Traditionally the rhyming scheme should also be double the common metre and be ABABCDCD, but it often uses the ballad metre style, resulting in XAXAXBXB. Examples of this variant are "America the Beautiful" and "It Came Upon the Midnight Clear". Likewise related is the common particular metre, 8.8.6.8.8.6., as in the tune Magdalen College, composed in 1774 by William Hayes, which has been used with the hymn "We Sing of God, the Mighty Source", by Christopher Smart.^[5]

Common metre is often used in hymns, like this one by John Newton.

Amazing Grace, how sweet the sound,
That saved a wretch like me!
I once was lost, but now am found,
Was blind, but now I see.

— from John Newton's "Amazing Grace"

William Wordsworth's "Lucy Poems" are also in common metre.

A slumber did my spirit seal;
I had no human fears:
She seemed a thing that could not feel
The touch of earthly years.

— from William Wordsworth's "A slumber did my spirit seal"

Many of the poems of Emily Dickinson use ballad metre.

Because I could not stop for Death,
He kindly stopped for me;
The Carriage held but just Ourselves
And Immortality.

— from Emily Dickinson's poem #712

Another American poem in ballad metre is Ernest Thayer's "Casey at the Bat":

The outlook wasn't brilliant for
The Mudville Nine that day;
The score stood four to two, with but
One inning more to play.

A modern example of ballad metre is the theme song to Gilligan's Island, infamously making it possible to sing any other ballad to that tune. The first two lines actually contain anapaests in place of iambs. This is an example of a ballad metre which is metrically less strict than common metre.

Just sit right back and you'll hear a tale,
a tale of a fateful trip.
That started from this tropic port,
aboard this tiny ship.

Another example is the folk song "House of the Rising Sun".

There is a house in New Orleans,
They call the rising sun.
And it's been the ruin of many a poor girl,
And God, I know I'm one.

"Gascoigns Good Night", by George Gascoigne, employs fourteeners.

The stretching arms, the yawning breath, which I to bedward use,
Are patterns of the pangs of death, when life will me refuse:
And of my bed each sundry part in shadows doth resemble,
The sundry shapes of death, whose dart shall make my flesh to tremble.

— from George Gascoigne's "Gascoigns Good Night"

"America the Beautiful" by Katharine Lee Bates employs the common metre double, using a standard CM rhyme scheme for the first iteration, and a ballad metre scheme for the second.

O beautiful for spacious skies,
For amber waves of grain,
For purple mountain majesties
Above the fruited plain!
America! America!
God shed his grace on thee
And crown thy good with brotherhood
From sea to shining sea!

Likewise "Advance Australia Fair" by Peter Dodds McCormick, Australia's national anthem:

Australians all let us rejoice,
For we are one and free;
We've golden soil and wealth for toil;
Our home is girt by sea;
Our land abounds in nature's gifts
Of beauty rich and rare;
In hist'ry's page, let ev'ry stage
Advance Australia Fair.
In joyful strains then let us sing,
Advance Australia Fair.

The first English dubbed Pokémon theme:

I want to be the very best,
Like no one ever was.
To catch them is my real test,
To train them is my cause.
I will travel across the land,
Searching far and wide.
Teach Pokémon to understand,
The power that's inside.

• Foot (prosody)
• Hymn tune
• Hymnology
• Hymns and hymn tunes
• Long metre
• Metre (hymn)
• Metre (poetry)
• Short metre