> ## Documentation Index
> Fetch the complete documentation index at: https://docs.arcuserp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Units of Measure

> Use Units of Measure settings to control quantity, weight, length, volume, and time units used by products, kits, orders, shipping, and inventory.

<Warning>
  Units affect quantities, dimensions, kit components, shipping, purchasing, and
  inventory history. Do not change a unit's meaning after it has been used on live records.
</Warning>

## Open Units Of Measure

1. Open **Settings**.
2. Choose **Entity Settings**.
3. Open **Products and Pricing**.
4. Choose **Units of Measure**.

<Frame caption={"Units of Measure is grouped by quantity, weight, length, volume, and time. System units are locked, while safe custom units can be managed by admins."}>
  <img src="https://mintcdn.com/arcuserp/ATYxy7SB_HGOBGqh/images/support/screenshots/settings/uom-settings.png?fit=max&auto=format&n=ATYxy7SB_HGOBGqh&q=85&s=4384aa47fbe28854f1f06ed060054435" alt="Units of Measure settings page showing quantity, weight, length, volume, and time tabs" width="1680" height="1060" data-path="images/support/screenshots/settings/uom-settings.png" />
</Frame>

## Understand Unit Types

| Type     | Common use                                                          |
| -------- | ------------------------------------------------------------------- |
| Quantity | Each, case, pallet, box, pack, or other count units.                |
| Weight   | Product weight, shipping weight, freight review, and carrier rules. |
| Length   | Product dimensions and package dimensions.                          |
| Volume   | Capacity or volume-based product data when needed.                  |
| Time     | Service or labor-style products when time units are used.           |

## Add A Custom Unit

1. Choose the correct unit type.
2. Click **Add Custom Unit**.
3. Enter a short code operators will understand.
4. Enter a clear label.
5. Choose the base unit.
6. Enter the conversion factor to the base unit.
7. Save and test the unit on a sample product.

<Frame caption={"The conversion factor tells Arcus how the custom unit relates to the base unit for that unit type."}>
  <img src="https://mintcdn.com/arcuserp/ATYxy7SB_HGOBGqh/images/support/screenshots/settings/uom-modal.png?fit=max&auto=format&n=ATYxy7SB_HGOBGqh&q=85&s=634b26b07b40561d6c2077e217f2d82e" alt="Add Custom Unit modal showing code, label, base unit, and conversion factor fields" width="960" height="900" data-path="images/support/screenshots/settings/uom-modal.png" />
</Frame>

## Safe Change Rules

* Create a new unit when the old unit has the wrong meaning.
* Deactivate a unit when it should no longer be selected.
* Keep system units locked.
* Test products, kits, purchasing, orders, and shipping after adding a unit.
* Avoid ambiguous codes such as box when the business uses multiple box sizes.

## Common Blocks

* **Unit is locked**: system units cannot be edited.
* **Unit cannot be deleted**: it may already be used. Deactivate it instead.
* **Conversion is wrong**: create a replacement unit and correct product setup intentionally.
* **Shipping rates look wrong**: check weight and dimension units on the product and package.
* **Kit quantities look wrong**: confirm component quantities use the expected unit.

## Related Articles

<CardGroup cols={2}>
  <Card title="Products and Pricing Settings" href="/support/settings/products-pricing">
    Manage pricing levels, categories, units, and adjustment rules together.
  </Card>

  <Card title="Product Setup" href="/support/products/setup">
    Create and maintain products that use units for quantity, dimensions, weight, and inventory.
  </Card>

  <Card title="Kits and Assemblies" href="/support/products/kits">
    Use component quantities and units safely when selling or building kits.
  </Card>

  <Card title="Shipping and Fulfillment Setup" href="/support/settings/shipping">
    Configure shipping behavior that depends on product dimensions and weight.
  </Card>
</CardGroup>