What does Instant mean in Grafana Prometheus queries?
Understand Instant versus Range queries, how the dashboard end time affects evaluation, and when to use each mode for stats, tables, and trends.
An Instant query evaluates a PromQL expression once. In Grafana, it normally evaluates at the end of the selected time range. A Range query evaluates the expression repeatedly across that range so a panel can display a trend.
Older Grafana interfaces expose an Instant checkbox. Newer Prometheus query editors offer Instant, Range, and Both query types.
Compare the query modes
| Mode | Typical result | Useful for |
|---|---|---|
| Instant | One value per returned series at one evaluation time | Stat, gauge, or current-state table |
| Range | Values at repeated evaluation steps | Time-series charts |
| Both | Results from both query types | Panels that need a trend and a separate latest-value result |
Instant does not mean that the dashboard time picker is ignored. Selecting a historical range also changes the evaluation time. Time-dependent variables used inside the expression can affect the query as well.
Choose the mode for the panel
Use Instant when a Stat panel or table needs one evaluation result per series. Use Range when you need to see how that result changed over time. A single instant result does not contain a historical curve; rendering it as a constant across the panel is a separate visualization behavior.
For example, this remains useful in Instant mode:
rate(http_requests_total[5m])
It calculates the five-minute rate ending at the chosen evaluation time. The expression's lookback window remains meaningful even though Grafana asks for only one evaluation.
Investigate mismatched values
If a Stat value differs from the end of a trend, inspect the panel's reduction, query timestamps, step alignment, and expressions. A range-based Stat may show a mean, maximum, or last value depending on its configuration. It does not always represent the same calculation as an Instant query.
Use the query inspector to compare the actual requests. An instant query often avoids repeated evaluations, but a wide selector or long subquery can still be expensive; it is not guaranteed constant-time work.
FAQ
Why is my time-series panel empty or flat? Check whether the query returns just one instant result and whether a constant transform or other field override is enabled. A flat line alone does not prove the underlying metric stayed constant.
Does {{instance}} still work in the legend? Yes. Returned labels are available for legend interpolation in either query mode.
Sources
This guide is based on the documentation below; the examples have not been tested against a live deployment.
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