---
title: "Create a Calculated Field"
method: POST
path: "/1/derived_columns/{datasetSlug}"
tags: ["Calculated Fields"]
---

# Create a Calculated Field

`POST /1/derived_columns/{datasetSlug}`

Create a Calculated Field (also called a Derived Column). Calculated Fields allow you to run queries based on the value of an expression that is calculated from the fields in an event.

## Request body

- CalculatedField
  - `id` string, required — Unique identifier (ID), returned in response bodies.
  - `alias` string, required — The human-readable name of the Calculated Field (also called Derived Column), as it will be referenced when building queries.
  - `expression` string, required — The expression to evaluate to construct this Calculated Field's value. (Calculated Field is also called Derived Column.) Refer to the [Calculated Field Reference](https://docs.honeycomb.io/reference/derived-column-formula/).
  - `description` string — A human-readable description for the Calculated Field that displays in the UI.
  - `created_at` string, required — ISO8601 formatted time when the field was created.
  - `updated_at` string, required — ISO8601 formatted time when the field was updated.

## Response `201`

Success

- CalculatedField
  - `id` string, required — Unique identifier (ID), returned in response bodies.
  - `alias` string, required — The human-readable name of the Calculated Field (also called Derived Column), as it will be referenced when building queries.
  - `expression` string, required — The expression to evaluate to construct this Calculated Field's value. (Calculated Field is also called Derived Column.) Refer to the [Calculated Field Reference](https://docs.honeycomb.io/reference/derived-column-formula/).
  - `description` string — A human-readable description for the Calculated Field that displays in the UI.
  - `created_at` string, required — ISO8601 formatted time when the field was created.
  - `updated_at` string, required — ISO8601 formatted time when the field was updated.

## Other responses

- `400` — The provided request body was invalid.
- `401` — Unauthorized
- `403` — Forbidden
- `404` — Not Found
- `409` — Conflict
- `429` — Rate Limit Exceeded

---

[API](https://skmtc.net/honeycomb/apis/honeycomb-api.md) · [All operations](https://skmtc.net/honeycomb/apis/honeycomb-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/honeycomb/honeycomb-api/revisions/117619fac2a5/schema)