Where exactly do you put the BPM in a Suno prompt?
Put it in the style or prompt box, not the lyrics box, right after the genre name so it reads as part of the core description: "synthwave, 100 BPM, driving arpeggio, punchy drums". Putting the number at the very end of a long prompt makes it less likely to be picked up, since later words carry less weight the longer the prompt gets.
Why does the tempo still drift?
Suno and Udio generate audio from a description, they do not run a metronome first and then compose to it, so the number is a strong suggestion rather than a hard setting. In practice this means a 90 BPM request can render at 87 or 94, and very slow or very sparse prompts sometimes render at double or half the number you asked for because the model reads the groove differently than the number.
Genres with a very distinctive pulse, like drum and bass at 174 BPM or house at 124 BPM, tend to hold tempo better than ambient or ballad styles where the beat is soft or absent.
What is double-time and half-time, and how does it cause drift?
Double-time means the drums or hi-hats subdivide twice as fast as the main pulse feels, and half-time means the snare or clap lands on beat 3 instead of beats 2 and 4, making a fast tempo feel slow. Trap at 140 BPM is a common example: it is often felt and described as 70 BPM half-time, so if you write 140 you may get fast hats over a slow-feeling groove, and if you write 70 you may get an unexpectedly sluggish track.
- For trap, hip-hop with a half-time feel, or ballads with double-time hats, name the feel as well as the number, e.g. "140 BPM, half-time feel".
- If the render comes back at the wrong speed, try stating the genre's most common tempo instead of an unusual one, since the model leans on genre defaults when the number and the genre don't usually go together.
Is there a way to actually lock the tempo instead of just suggesting it?
Not with the prompt alone: on Suno, Udio and Lyro Music’s song models alike, the number is a strong hint, not a lock. Two things do get you an exact tempo.
- Fit the song to the tempo afterwards. In Lyro Music’s studio, set the project to the BPM you wanted, select the clip and choose Fit to project tempo. Lyro measures the clip’s tempo and stretches it to the project’s, so a song that came back at 87 BPM instead of 90 is brought to 90. It works for changes up to 25% and needs a steady tempo to measure.
- Start from a beat that is already at that tempo. Make the instrumental at the exact BPM, or bring one you have, and have Lyro sing your lyrics on it. The beat file is never regenerated or changed, so it stays at exactly its tempo, and the vocal comes back as its own track.
Both matter for anything that has to sync to a click, a video cut or another track. If you only need the right feel, hip-hop instrumentals commonly sit at 80 to 100 BPM, most often 85 to 95.
Common mistakes
- Writing the BPM at the very end of a long prompt: move it right after the genre name near the start.
- Naming a tempo that fights the genre's usual feel, like "ballad, 174 BPM": use the genre's typical range or state the feel explicitly.
- Assuming the number is exact: treat it as a target and expect a few BPM of drift either way.
- Repeating the BPM in both the style box and the lyrics box: this doesn't reinforce it and can confuse section structure.
- Needing a genre with a half-time or double-time feel but only giving the number: add "half-time feel" or "double-time hats" so the groove matches the tempo you meant.