---
title: Create a metric in Optimizely with the metric builder
slug: experimentation-strategy/docs/create-a-metric-in-optimizely-with-the-metric-builder
createdAt: 2026-08-05T20:33:25.831Z
---

- Optimizely Web Experimentation
- Optimizely Personalization
- Optimizely Performance Edge
- Optimizely Feature Experimentation
- Optimizely Full Stack (Legacy)

The natural-language metrics builder in Optimizely Experimentation and Optimizely Personalization lets you define and add [metrics](docId\:QMhSl6-5c54bbhHlZwMcp) to your experiments and campaigns. It asks you to define a small set of parameters that tell Optimizely how to measure and report the results. These parameters include the following:

- The winning direction (increase or decrease).
- What you want to measure (the *numerator*).
- The rate at which you want to measure it (the *denominator*).

## The metrics builder

Use the metrics builder to create your metrics directly in your experiment. First, select your metric type, then fill out the rest of the builder with your information.

:::hint{type="info"}
**Note**

Several metric types have additional requirements you should know.

- [Bounce rate and exit rate metrics](docId\:ZNw3FvHTBv1wh4QbOh708) (Optimizely Web Experimentation only).
- [Total value](docId\:eUlGyGyAuaLf68o_GQvJD).
- [Total revenue in Web Experimentation](docId\:Tfs7x7ZmcKDsfS3nXhS3V) and [Total revenue in Feature Experimentation](docId\:E4kGQiwGcruXWHm-1n_HW).
- [Ratio metrics](docId\:njoNA36ZPt_NpzbeCVtYL).
:::

The metrics builder UI varies slightly between regular and ratio metrics. See the following sections for examples.

### Regular metrics

Regular metrics include the following types: **Click Event Metric**, **Custom Event Metric**, **Overall Revenue**, and **Page Event Metric**.

- Optimizely Web Experimentation
- Optimizely Personalization
- Optimizely Performance Edge
- Optimizely Feature Experimentation

![WebMetrics\_EventProperties.png](https://api.archbee.com/api/optimize/BrbvVORKJ5iIeSMZye5kI/jroj5-OYwd_ih1b7xIT6e-20260720-144807.png)

1. Name
2. [Event](docId\:puGm9z4XkEG5PDkyaNmlA)
3. [Winning direction](docId\:cphstZe3xKhsY7WsnnLZK)
4. [Numerator (aggregator)](docId\:cphstZe3xKhsY7WsnnLZK)
5. [Denominator](docId\:cphstZe3xKhsY7WsnnLZK)

If **Filter this metric on event properties** is selected, the following display:

6. [Event property](docId\:cphstZe3xKhsY7WsnnLZK)
7. [Condition](docId\:cphstZe3xKhsY7WsnnLZK)
8. [Value being evaluated](docId\:cphstZe3xKhsY7WsnnLZK)

### Ratio metrics

- Optimizely Web Experimentation
- Optimizely Personalization
- Optimizely Performance Edge
- Optimizely Feature Experimentation

![](https://api.archbee.com/api/optimize/BrbvVORKJ5iIeSMZye5kI/XeOAOvPw5Ccn8Dp8c74ik-20260720-144807.png)

1. Name
2. [Winning direction](docId\:cphstZe3xKhsY7WsnnLZK)
3. [Numerator (aggregator)](docId\:cphstZe3xKhsY7WsnnLZK) event
4. How to count the numerator event. Options include the following:
   - Unique conversions
   - Total conversions
   - Total revenue
   - Total value
5. [Denominator](docId\:cphstZe3xKhsY7WsnnLZK) event
6. How to count the denominator event. Options include the following:
   - Unique conversions
   - Total conversions

### Winning direction

The winning direction parameter (**Increase** or **Decrease**) defines the desired outcome for the metric in your experiment or campaign. This direction indicates whether an increase or decrease in the metric value is preferable.

- **Increase** – For most metrics, such as revenue or conversions, a higher value signifies success. An increase in these metrics typically indicates positive performance.
- **Decrease** – For some metrics, like bounce rate or cart abandonment, lower values represent an improvement. A decrease in these metrics typically indicates a positive performance.

By setting the winning direction, you guide Optimizely in evaluating and reporting the success of your experiments based on the desired changes in your metrics.

### Numerators

The metrics builder has different types of metrics templates, also called numerators. You should select your metric's numerator based on the specific questions you want your experiment to answer.

- **Unique conversions** – Number of visitors with at least one conversion.
- **Total conversions** – The total number of conversions.
- **Total revenue** – The total revenue generated. You must [configure revenue tracking in Optimizely Web Experimentation](docId\:Tfs7x7ZmcKDsfS3nXhS3V) or [revenue event tags in Optimizely Feature Experimentation](docId\:E4kGQiwGcruXWHm-1n_HW) first.
- **Total value** – The total of any other numerical value. See [Total value and other numeric metrics](docId\:eUlGyGyAuaLf68o_GQvJD).
- **Bounce Rate** (Optimizely Web Experimentation only) – The total number of times where the page is viewed is the first and only page the visitor sees before leaving your site.
- **Exit Rate** (Optimizely Web Experimentation only) – The total number of times where the page is viewed is the last page the visitor sees before leaving your site.

For ratio metrics, numerators can include unique conversions (unique count), total conversions (total count), total revenue, or the total value of the event you have selected.

For more details on each metric type, see [Types of metrics and when to use them](docId:8gpGLNz8DTMSwpnQ_giQj).

### Denominators

The metrics builder's denominators are the rate at which your metric measures its numerator. For example, you could measure unique conversions per session or total revenue per conversion.

Because of the inherent differences between metric types and the differences between Optimizely campaigns and experiments, not every denominator works with every numerator.

| Numerators                                       | Experiment type                     | Possible denominators |             |                |
| ------------------------------------------------ | ----------------------------------- | --------------------- | ----------- | -------------- |
|                                                  |                                     | Per visitor           | Per session | Per conversion |
| **Unique conversions** and **total conversions** | Optimizely Personalization campaign | No                    | Yes         | No             |
| **Unique conversions** and **total conversions** | Experiment                          | Yes                   | No          | No             |
| **Bounce rates** and **exit rates**              | Any                                 | No                    | Yes         | No             |
| **Total revenue** and **total value**            | Optimizely Personalization campaign | No                    | Yes         | Yes            |
| **Total revenue** and **total value**            | Experiment                          | Yes                   | No          | Yes            |

For ratio metrics, the choices for the denominator are total count (total conversions) or unique count (unique conversions) of a second event.

Optimizely's [Stats Engine](docId\:e7e-S6BollFwcP1RX9YS_) uses [false discovery rate control](docId:8ddaVTjTgUbrnQRJx5I8m) to reduce your chance of making an incorrect business decision or implementing a false positive among conclusive results. To learn how Stats Engine prioritizes primary metrics, secondary metrics, and monitoring goals, see Optimizely's [Stats Engine approach to metrics and goals](docId\:oWMQ0BWo1DoM2WWKINZSP).

### Event property

Event properties can be added to your event during creation. When you send Optimizely events, you can add additional information about the product or action performed. This lets you track and view additional information on [the Optimizely Experimentation Results page](docId\:mrUblIuNVOZc1dvjWdsbw).

### Condition

The event property's condition indicates how the value is evaluated. Depending on the event property's type, the following are the different possible conditions:

- **String** – Is, Is not, Contains, Does not contain
- **Number** – =, \<, ≤, >, ≥
- **Boolean** – Is, Is not

### Value being evaluated

You define what value the property event should or should not evaluate to count as a metric.

## Open the metrics builder in Optimizely Web Experimentation and Optimizely Personalization

1. Go to **Experiments** and click on the experiment. If using Personalization, go to **Optimizations** and choose your campaign or experiment.
2. Click **Track > Metrics** to open the metrics tab.
3. Select an event or click **Add Metric** to open the metrics builder.

![](https://api.archbee.com/api/optimize/BrbvVORKJ5iIeSMZye5kI/N9yfEkNLRrT1m5_lBeBJL-20260720-144807.png)

Optimizely Web Experimentation and Optimizely Personalization offer several pre-built metrics and a flexible numerator called total value. If you are unsure which metric to choose, see [Types of metrics and when to use them](docId:8gpGLNz8DTMSwpnQ_giQj).

To learn how to edit your metrics when you build them, see [Edit a metric](docId\:cWthLnXH2Y37EJdZLbM77).

## Open metrics builder in Optimizely Feature Experimentation

1. Go to **Flags** and click on the flag.
2. Click the A/B test or multi-armed bandit rule.
3. Click **+ Add Metric**.

   ![](https://api.archbee.com/api/optimize/BrbvVORKJ5iIeSMZye5kI/oAW-kUvMm-6BJJx9Jm-S3_45426613851405.png)