---
title: "Multidimensional SLI example | Grafana Cloud documentation"
description: "Learn what multidimensional SLIs are in Grafana SLO, how they work with Prometheus metrics."
---

# Multidimensional SLI example

This guide explains what multidimensional SLIs are, how they work, how they compare with aggregated SLIs, and provides a basic example.

**Before you begin**, read the [SLI availability examples and SLI query requirements](/docs/grafana-cloud/alerting-and-irm/slo/sli-examples/availability/) to understand how SLIs are defined in Grafana SLO.

In the previous availability and latency SLI examples, SLIs are calculated using the ratio of successful event rates formula:

![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```none
Success ratio = rate of successful events over a period
                /  
                rate of total events over a period
```

However, this formula is incomplete, because Prometheus queries **can return multiple series** (also called dimensions).

In practice, the final SLI uses `sum(...)` to aggregate results from all series. The formula looks more like:

![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```none
Success ratio = sum(rate of successful events over a period)
                /  
                sum(rate of total events over a period)
```

Here, `sum(...)` aggregates all dimensions (distinct label values) in the numerator and denominator before the final ratio calculation. This type of SLI is referred to as a **roll-up or aggregated SLI**, where the SLI result returns only one series (dimension):

[Roll-up SLI returns a single aggregated dimension](/media/docs/grafana-cloud/slo/multidimensional-single-dimension-graph.png)

## Multidimensional probe example

**Multidimensional SLIs** (SLIs evaluated across multiple label dimensions) use `sum by (<labels>)` in both the numerator and denominator, producing multiple ratio series. For example:

![Copy code to clipboard](/media/images/icons/icon-copy-small-2.svg) Copy

```none
Success ratio = sum by (probe) (rate of successful probe executions)
                /  
                sum by (probe) (rate of total probe executions)
```

Expand table

| Dimension           | Success ratio per dimension |
|---------------------|-----------------------------|
| {probe=“Calgary”}   | 0.9                         |
| {probe=“CapeTown”}  | 1                           |
| {probe=“Hyderabad”} | 0.95                        |

The final SLI result is `0.9`, equal to its equivalent roll-up SLI.

All dimensions are aggregated in the final SLI calculation, so for SLO compliance it behaves as a roll-up SLI.

The next example replicates the [probe availability (summary) example](/docs/grafana-cloud/alerting-and-irm/slo/sli-examples/availability/#probe-availability-summary), using the **Grouping** function to define dimensions per `probe`:

[Multidimensional SLI created using the Ratio option, showing per-probe SLI results](/media/docs/grafana-cloud/slo/multidimensional-probe-sli-example2.png)

You can also create multidimensional SLIs using the **Advanced** option to write the SLI query directly.

> Note
> 
> Each SLO creates a few recording rules that generate computed series for calculating the SLI and error budget more efficiently.
> 
> Multidimensional SLOs multiply the number of SLO series generated for each dimension, increasing the number of produced [active series and data points per minute (DPM)](/docs/grafana-cloud/cost-management-and-billing/manage-invoices/understand-your-invoice/metrics-invoice/).

## How multidimensional SLIs work

**For SLO compliance evaluation, the SLI calculation for multidimensional and roll-up SLIs is exactly the same**.

However, Grafana SLO provides additional functionality to handle multidimensional SLIs:

1. **Fast and slow burn alerts per dimension**. When enabled, Grafana SLO triggers fast-burn or slow-burn alerts whenever an individual dimension consumes the error budget quickly or slowly, respectively.
   
   [The SLO dashboard displays the list of multidimensional alerts](/media/docs/grafana-cloud/slo/slo-dashboard-with-multidimensional-alerts4.png)
   
   > Note
   > 
   > Multidimensional alerts are not triggered for overall SLO consumption, but only for the consumption of a particular dimension.
   > 
   > To be alerted when the overall error budget is consumed, create a roll-up SLO that does not include the `sum/group by` dimensions.
2. **Per-dimension SLO dashboard filtering**. The SLO dashboard allows filtering results and visualizing SLI consumption for each dimension.
   
   [](/media/docs/grafana-cloud/slo/slo-dashboard-with-multidimensional-sli4.png)

> Tip
> 
> In Grafana Play, you can explore and compare [multidimensional](https://play.grafana.org/d/grafana_slo_app-a9dcui8yk2y5op170e3ju?tech=docs&pg=slo-examples&plcmt=callout-tip&cta=slo-multidimensional) and [non-multidimensional](https://play.grafana.org/d/grafana_slo_app-rlunhe4nr27czbhprxepv?tech=docs&pg=slo-examples&plcmt=callout-tip&cta=slo-multidimensional-single) SLOs. In the multidimensional SLO, you can filter by dimensions and observe error budgets and SLI values in real time, then click **Explore SLI Query** to inspect the underlying queries.

## When to use multidimensional SLIs

Avoid using high-cardinality labels as dimensions, as this can lead to excessive series and inefficient SLI evaluation. To learn more about how Grafana evaluates metrics with multiple label dimensions, refer to [multidimensional alert examples](/docs/grafana-cloud/alerting-and-irm/alerting/best-practices/multi-dimensional-alerts/).

Multidimensional SLIs are useful when you want to observe SLI behavior across multiple dimensions, such as probe locations, regions, or services.

Use multidimensional SLIs when:

- You want visibility into per-dimension SLI behavior.
- You need per-dimension alerting (for example, burn-rate alerts per probe).
- Individual dimensions need to be observed separately.

Multidimensional SLIs do not change how SLO compliance is evaluated. For SLO compliance, all dimensions are aggregated into a single roll-up SLI.