Temperature vs Top-P Sampling
Temperature reshapes how sharply a model favors its top-probability tokens; top-p trims which tokens are even eligible to be sampled. They tune together, not against each other.
| Dimension | Temperature | Top-P (Nucleus) Sampling |
|---|---|---|
| What it actually controls | Rescales the shape of the probability distribution — sharper toward the top choice, or flatter toward the whole vocabulary. | Restricts which tokens are eligible to be sampled at all, regardless of how the distribution is shaped. |
| Behavior at extreme settings | At 0, sampling becomes fully deterministic — the model always takes its single highest-scoring token. | At a very low value, the nucleus can shrink to just one or two tokens; near 1, it barely restricts anything. |
| Adapting to model confidence | Applies the same rescaling regardless of how confident the model is at that step. | Wins here The eligible set shrinks automatically when the model is confident and grows when it is genuinely uncertain. |
| Guarding against near-nonsense tail tokens | Even lowered, some probability mass still touches every token in the vocabulary. | Wins here Can zero out the long tail entirely, regardless of how temperature shaped the rest of the distribution. |
| Interpretability of the setting itself | Wins here A single scaling factor that is straightforward to reason about directly. | Its practical effect depends on the shape of the distribution at each step, harder to predict in the abstract. |
| Common production default | Rarely set alone in serious systems. | Rarely set alone either — most APIs ship sensible defaults for both together (e.g., temperature around 0.7-1.0 with top-p around 0.9-0.95). |
| Task fit | Low values suit tasks with one right answer: code, extraction, math. | A moderate value paired with a moderate temperature suits creative or varied-phrasing tasks without inviting nonsense. |
When to choose Temperature
Reach for temperature as the single dial to move between deterministic and exploratory output when rare tail tokens aren't a specific concern.
When to choose Top-P (Nucleus) Sampling
Reach for top-p when you want variety without occasionally sampling near-nonsense from the tail, especially once temperature is raised.
The verdict
This isn't really an either/or choice — they are independent dials solving different problems, and nearly every production system sets both together rather than treating them as alternatives.