--- title: SLO Type Comparison description: Datadog, the leading service for cloud-scale monitoring. breadcrumbs: Docs > Service Level Objectives > SLO Guides > SLO Type Comparison --- # SLO Type Comparison ## Overview{% #overview %} When creating SLOs, you can choose from the following types: - **Metric-based SLOs**: can be used when you want the SLI calculation to be count-based, the SLI is calculated as the sum of good events divided by the sum of total events. - **Monitor-based SLOs**: can be used when you want the SLI calculation to be time-based, the SLI is based on the Monitor's uptime. Monitor-based SLOs must be based on a new or existing Datadog monitor, any adjustments must be made to the underlying monitor (cannot be done through SLO creation). - **Time Slice SLOs**: can be used when you want the SLI calculation to be time-based, the SLI is based on your custom uptime definition (amount of time your system exhibits good behavior divided by the total time). Time Slice SLOs do not require a Datadog monitor, you can try out different metric filters and thresholds and instantly explore downtime during SLO creation. {% alert level="info" %} The supported history duration for Metric-based and Time Slice SLOs matches your account's metric duration (by default, this is 15 months). {% /alert %} ## Comparison chart{% #comparison-chart %} | **Metric-based SLO** | **Monitor-based SLO** | **Time Slice SLO** | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Supported data types** | Metrics with type of count, rate, or distribution | Metric Monitor types, Synthetic Monitors, and Service Checks | All metric types (including gauge metrics) | | **Functionality for SLO with Groups** | SLO calculated based on all groupsCan view all groups in SLO side panel and SLO widget | Supported for SLOs with a single multi alert Monitor**Option 1:** SLO calculated based on all groups (can view all groups in SLO side panel and SLO widget)**Option 2:** SLO calculated based on up to 20 selected groups (can view all selected groups in SLO side panel and SLO widget) | SLO calculated based on all groupsCan view all groups in SLO side panel and SLO widget | | **SLO side panel** | Can set custom time windows to view up to 15 months of SLO history | Can set custom time windows to view up to 15 months of SLO history | Can set custom time windows to view up to 15 months of SLO history | | **SLO alerting ([Error Budget](https://docs.datadoghq.com/service_level_objectives/error_budget.md) or [Burn Rate](https://docs.datadoghq.com/service_level_objectives/burn_rate.md) Alerts)** | AvailableIf groups are present, can alert based on overall SLO only | Available for SLOs based on Metric Monitor types only (not available for Synthetic Monitors or Service Checks)If groups are present, can alert based on overall SLO only | AvailableIf groups are present, can alert based on groups or overall SLO | | [**SLO Status Corrections**](https://docs.datadoghq.com/service_level_objectives.md#slo-status-corrections) | Correction periods are ignored from SLO status calculation | Correction periods are ignored from SLO status calculation | Correction periods are counted as uptime in SLO status calculation | | **SLO widgets ([SLO List widget](https://docs.datadoghq.com/dashboards/widgets/slo_list.md) or [SLO widget](https://docs.datadoghq.com/dashboards/widgets/slo.md))** | Can view up to 15 months of historical data with the SLO widget | Can view up to 15 months of historical data with the SLO widget | Can view up to 15 months of historical data with the SLO widget | | **[SLO Data Source](https://docs.datadoghq.com/dashboards/guide/slo_data_source.md) (up to 15 months of historical data)** | Available | Not available | Available | | **Handling missing data in the SLO calculation** | Missing data is ignored in SLO status and error budget calculations | Missing data is handled based on the [underlying Monitor's configuration](https://docs.datadoghq.com/service_level_objectives/monitor.md#missing-data) | Missing data is treated as uptime in SLO status and error budget calculations | | **Uptime Calculations** | N/A | Uptime calculations are based on the underlying MonitorIf groups are present, overall uptime requires *all* groups to have uptime | [Uptime](https://docs.datadoghq.com/service_level_objectives/time_slice.md#uptime-calculations) is calculated by looking at discrete time chunks, not rolling time windowsIf groups are present, overall uptime requires *all* groups to have uptime | | **[Calendar View](https://docs.datadoghq.com/service_level_objectives.md#slo-calendar-view) on SLO Manage Page** | Available | Not available | Available | | **Public [APIs](https://docs.datadoghq.com/api/latest/service-level-objectives.md) and Terraform Support** | Available | Available | Available | ## Best practices for choosing an SLO Type{% #best-practices-for-choosing-an-slo-type %} - Whenever possible, use metric-based SLOs. It's best practice to have SLOs where the error budget reflects the number of bad events you have left before you breach your SLO. Your SLO calculations will also be volume weighted based on the number of events. - If, instead, you want an SLO that tracks uptime and uses a time-based SLI calculation, use time slice SLOs. Unlike monitor-based SLOs, time slice SLOs don't require you to maintain an underlying monitor for your SLO. - Finally, consider monitor-based SLOs for use cases that are not covered by time slice SLOs, which include SLOs based on non-metric monitors or multiple monitors. ## Further Reading{% #further-reading %} - [Overview of Service Level Objectives](https://docs.datadoghq.com/service_level_objectives.md) - [Metric-based SLOs](https://docs.datadoghq.com/service_level_objectives/metric.md) - [Monitor-based SLOs](https://docs.datadoghq.com/service_level_objectives/monitor.md) - [Time Slice SLOs](https://docs.datadoghq.com/service_level_objectives/time_slice.md) - [Best practices for managing your SLOs with Datadog](https://www.datadoghq.com/blog/define-and-manage-slos/)