---
title: 6.8.1 Unit Conversion for Numerical Observations
description: "# Unit Conversion for Numerical Observations In the OBSERVATION_FACT table the UNIT_CD column stores the unit value for your numerical observations. An example of a value in UNIT_CD would be **mg** for milligram or **gm** for gram. Although i2b2 recommends…"
url: "https://i2b2.org/docs/6-8-1-unit-conversion-for-numerical-observations/"
updated: "2026-09-15"
category: i2b2 Installation Guide / Chapter 6. Initial Setup of i2b2 in Admin / 6.5 Optional Parameters
---

# 6.8.1 Unit Conversion for Numerical Observations

# Unit Conversion for Numerical Observations

In the OBSERVATION_FACT table the UNIT_CD column stores the unit value for your numerical observations. An example of a value in UNIT_CD would be **mg** for milligram or **gm** for gram.

Although i2b2 recommends the units be normalized to a single unit we also recognize this is not always possible. In this instance, you may wish to have the units converted automatically when running a query in which a value constraint is defined. To turn this feature on you would add the following parameter to the **Project** you want it applied.

**Type of Parameter:** Project Parameter

**Parameter Name:** CRC_ENABLE_UNITCD_CONVERSION

| Value | Description |
| --- | --- |
| ON | Enables unit conversion |
| OFF | Disables unit conversion *(default setting)* |

Note

The parameter does not change the data stored in the database. It is simply applied when the query is run.

For steps on how to add a project parameter please see the section titled *Add Project Parameters* located in this chapter.