Extend from before the cut

The song is three verses long and the file stops in the middle of the second one. Or the words all fit and there are eleven seconds of music left at the end, which is not a song either.

Extend is the feature for this, and where you start it matters more than what you paste into it.

Start the extension before the truncation, not at it

Suno's Extend asks you where in the existing audio to continue from. The instinct is to pick the very end, since that is where the song stopped. That gives the model the least possible context: a bar of whatever was happening when the generation ran out.

Set the start five to ten seconds earlier, inside the last passage you can actually hear, and the continuation has a phrase to follow. A commenter on the beginner's guide thread describes the same mechanism from the other direction: extending from 0:05 of a take they liked returned "very similar or exactly the same soundtrack with different voices". Where you start decides what carries over.

Then paste only what has not been sung, starting with the section it belongs to:

Extend box, the way that wastes a generation
[Verse 1]
Rain on the window of the second floor
I never learned to sleep before the sun

[Chorus]
Call me when you land

[Verse 2]
The suitcase is still open on the bed

The model has already sung verse one and the chorus. Handing them back means it either sings them again or spends its budget deciding not to. What it needs is the remainder, with one line of overlap so it knows where it is:

Extend box, from six seconds before the cut
[Chorus]
Call me when you land

[Verse 2]
The suitcase is still open on the bed
I moved it once and put it back again

The opposite failure is a song that will not stop

The thread about extend not ending a song from January 2025 is the mirror image, and its comments are a fair map of what people try.

The most popular suggestion is a question rather than a report: has anyone tried [End]? Below it, somebody writes [SHORT-END-FADEOUT] into both the style and the lyrics box, somebody else swears by [Final note sustains], and one reply has no magic in it at all: download the file and fade it in Audacity.

One reply offers a mechanism instead: Suno tries to fill each section close to a time limit, around four minutes for a first generation and two for an extension, so the fix is to give it enough lyrics to reach that naturally rather than leaving it to invent an outro. That is one person's model of the behavior rather than a documented rule, and it predicts something you can check on your own takes.

Note

Both failures come from the same place. The generation has a fixed amount of audio to fill, and it will fill it, with your words if you gave it the right number and with something else if you did not.

Cutting off mid-word is a length problem first

Before reaching for Extend, look at how much you asked for. The October 2024 thread about songs cutting off mid-lyric has a reply describing exactly this: the model goes on to repeat a verse it has no chance of fitting in.

Guides recommend building longer songs from more sections rather than longer ones, and HookGenius suggests 8 to 12 sections and 6 to 8 lines per verse for a three to four minute track. Whether that produces length reliably is not something anyone has measured, so treat it as a starting shape rather than a lever.

Replace Section when only one passage is wrong

If the song is the right length and one part is bad, Extend is the wrong tool. Suno's Replace Section rewrites a selected range in place, which keeps everything around it, and it is worth reaching for when a single line lands badly. Expect the surrounding voice to shift slightly at the seam, and keep the replaced range short.

What Extend will not do

It will not give you a clean join every time. The extension is a fresh generation that begins from a point in the old one, so there is a moment where the arrangement decides again, and a bad seam is a reason to move the start point rather than to keep the take.

It also will not save a sheet that was too long to begin with. If the first generation ran out with two sections left, the second one will run out too unless you give it less to sing.

Play your last truncated take, note the time six seconds before the cut, and start there.