UX benchmarking is the process of evaluating a product or service’s user experience by using metrics to gauge its relative performance against a meaningful standard. These metrics are usually collected using quantitative usability testing, analytics, or surveys.
Consider conducting a benchmarking study if you want to:

To conduct an end-to-end UX benchmarking study, first decide what you’re going to measure and which research method you’ll use to collect those metrics. Next, collect your first measurement, redesign the product, and collect an additional measurement. Then, compare and interpret your findings, and possibly calculate ROI. Once you’ve completed the initial end-to-end process, future iterations of your study (assuming that the context remains the same) can begin at step 4 (redesign the product).
Focus on the key metrics that best reflect the quality of the user experience you’re interested in evaluating. Look for metrics that translate to UX and organizational goals.
That said, before you determine which metrics to collect, you must define the context of your study. In other words, consider:
Figure out the top tasks that users complete in your product. If your organization doesn’t have existing top tasks, you can start by documenting (most) tasks in the product. Then, prioritize the list of tasks and select approximately 5–10 that are most important to your users.