Find the words and lines that will fight a singer — consonant piles, closed vowels on long notes, and lines nobody can get through in one breath.
A line can read beautifully and be impossible to sing. The failure is almost always mechanical: three consonants in a row where the melody wants to move, a short closed vowel sitting on the longest note in the phrase, or a rhyming word that ends in a cluster you cannot hold. This tool scores every line against those problems and names the specific words causing them.
Run the check and the report shows up here.
What actually makes a line hard to sing
Sung vowels are the note; consonants are the interruption. Open vowels — ah, oh, ay, ee, oo — can be sustained and tuned. Short closed vowels like the one in “sit” or “bet” cannot be held without distorting, and nasals (a word ending in -m, -n or -ng) stop the airflow entirely. So the worst possible place for the worst possible word is the end of a line on a long note, which is exactly where rhymes live.
Consonant clusters are the second problem. “Asked” is one syllable and five letters of difficulty: a vowel, then s, k and t in a row. At 96 BPM you have perhaps a quarter of a second to get through that. Multiply it across a line — “strengths”, “worlds”, “clenched” — and the singer is playing a percussion part with their tongue while trying to hold a melody.
How to use the result
- Fix the last word of a line first. That is where the long note lands, and swapping the rhyme for one ending in an open vowel usually fixes more than any other single change.
- A cluster at the start of a word is harder than one at the end, because the singer is arriving at the note cold. “Street” is harder than “east”.
- Function words stacked before the rhyme word are not a pronunciation problem, they are a rhythm problem. Three unstressed syllables in a row leave the rhyme word with nowhere to land.
- The breath budget is a rough guide, not a limit. Trained singers manage more; a writer demoing their own song in one take manages less. Adjust the tempo and re-run.
Questions people ask
- How is the breath budget calculated?
It allows roughly eight syllables per two bars at the tempo you set, scaling with beats per line. It is deliberately generous — it is there to catch lines that are obviously too long, not to police phrasing.
- Why is a word flagged that I sing fine?
Because this works from spelling, not sound, and because difficulty is personal. A cluster that is easy for one singer is impossible for another. Treat the flags as a prompt to try the line out loud, not as a verdict.
- Does this matter for rap or spoken styles?
Less, but not zero. Consonant density still governs how fast you can articulate, and closed vowels still will not sustain. The breath budget matters most of all here.
- Should I rewrite every flagged word?
No. Some difficulty is texture — a hard consonant on a downbeat can be exactly what a line needs. Change the ones that sit on long notes and leave the ones that pass quickly.
What this tool does not do. It reads spelling, not pronunciation, so it cannot know that “though” is easy and “through” is a cluster, and it cannot hear your melody, your range or your singer. Nothing here is a judgement about whether a line is good. Nothing is uploaded; everything runs in your browser and works offline. See the site disclaimer. Written by Nico, who builds these tools and writes about writing at WrittenTone.