--- title: "About availability calculation" description: "Quantities of items on hand at warehouses are automatically updated only after the documents that record inventory transactions are released or posted." lang: en languages: en: https://docs.vismasoftware.no/visma-net-erp/help/inventory/manage-availability-data/about-availability-calculation/index.md lastmod: 2026-02-19 --- > Documentation index: https://docs.vismasoftware.no/visma-net-erp/help/inventory/manage-availability-data/llms.txt # About availability calculation Last modified February 19, 2026 > Quantities of items on hand at warehouses are automatically updated only after the documents that record inventory transactions are released or posted. ## On hand quantities vs. actual quantities On-hand quantities (also referred to as **book quantities** ) usually differ from actual quantities on hand because during document processing, certain quantities of items can be: + booked on sales orders, + picked for shipping, + returned from customers, + ordered from suppliers, + in transit between warehouses. Visma Net gives you real-time visibility into available inventory, thus improving customer service. ## Configuration of availability data Configure the way availability data is calculated in accordance with your company's policies. You specify calculation options for each item class in the [Item classes (IN201000)](https://docs.vismasoftware.no/visma-net-erp/help/inventory/inventory-windows/item-classes-in201000/index.md) window. ## Types of quantities calculated The available quantities of items are calculated at the location level. ### Damaged or returned items Some warehouse locations may hold some quantities of damaged or returned items, and those quantities generally cannot be used for sale and should not be included in the quantities available. > [!NOTE] > If the **Multiple warehouse locations** functionality is disabled in the [Enable/disable functionalities (CS100000)](https://docs.vismasoftware.no/visma-net-erp/help/common-settings/enable-or-disable-functionalites/enable-disable-functionalities-cs100000/index.md) window, all the quantities available for a single default location of each warehouse are included in the availability data. For more information, see: [About warehouses and warehouse locations](https://docs.vismasoftware.no/visma-net-erp/help/inventory/manage-warehouses/about-warehouses-and-warehouse-locations/index.md). ### List of item quantities maintained in the system For each item, the quantities summarised below are maintained in the system and available for viewing on any window where you choose a stock item for adding to the document.
Option Description
Quantity on hand The on-hand quantity is the quantity of items (expressed in the base unit of measure) that are physically in stock and immediately available. The on-hand quantity of items is affected only by released documents.
Quantity not available

For each location in a warehouse, you can specify whether quantities at the location will be included in the quantity available.

For example: Items should not be included in quantities available for locations dedicated to items that are:

  • consigned
  • damaged
  • returned
  • in need of repair.
Total addition and total deduction

The Inventory allocation details (IN402000) inquiry window shows Total addition and Total deduction, which have values calculated based on unreleased documents with various statuses.

Total addition is the quantity of base units of the stock item on:

  • unreleased purchase orders,
  • receipts,
  • incoming transfers.

For each item class, you can specify which of the listed quantities should be included in this value for items of the class.

Total deduction is the quantity of base units of the stock item on:

  • unreleased sales orders,
  • inventory issues,
  • shipments,
  • transfers, and
  • kit assembly documents,
  • plus the non-available quantity.

For each item class, you can specify which of the listed quantities should be included in the total deduction quantity for items of the class in accordance with policies established in your organization.
Quantity available

For each item, the quantity available is calculated as Quantity on hand + Total addition - Total deduction.

This value is calculated in accordance with the options selected in the Item class window for the item class.
Quantity available for shipping

This quantity is calculated by the system as the on-hand quantity with quantities on issues and quantities shipped and on shipping deducted.

This calculation is not affected by any options selected by users.
## Allowing negative item quantity If the **Allow negative quantity** check box is selected in the [Item classes (IN201000)](https://docs.vismasoftware.no/visma-net-erp/help/inventory/inventory-windows/item-classes-in201000/index.md) window, Visma Net allows a negative on-hand quantity for items of the class. Warnings are issued on transactions that will result in negative inventory quantities. Location-level negative quantity can occur due to: + errors on inventory documents + incorrect quantities specified or wrong locations + delayed release of receipt or transfer documents confirming the actual arrival of goods. Stocktaking count can be undertaken for items with negative on-hand quantities. ## Option to include quantity as available at location If the **Include in qty. available** option is selected for the location in the [Warehouses (IN204000)](https://docs.vismasoftware.no/visma-net-erp/help/inventory/inventory-windows/warehouses-in204000/index.md) window, the quantities available at the location will be added to the quantity available. If the option is not selected, those quantities will be added to the quantity not available. As a result, for each warehouse, the total quantities available and unavailable are calculated as the sum of respective quantities for all warehouse locations. ## Viewing availability information Visma Net availability data allows you to get complete inventory visibility in all distribution-oriented workspaces, so you can provide better customer service and reduce inventory carrying costs: + For each item, you can view summary information about various quantities of this stock item at various warehouses and locations using the [Inventory summary (IN401000)](https://docs.vismasoftware.no/visma-net-erp/help/inventory/inventory-windows/inventory-summary-in401000/index.md) window. + For each stock component of a kit, using the [Kit assembly (IN307000)](https://docs.vismasoftware.no/visma-net-erp/help/inventory/inventory-windows/kit-assembly-in307000/index.md) window, you can view the availability data at the bottom of the screen. + For each item, you can view complete information about how its quantities are allocated (in accordance with unreleased documents) at a particular warehouse using the [Inventory allocation details (IN402000)](https://docs.vismasoftware.no/visma-net-erp/help/inventory/inventory-windows/inventory-allocation-details-in402000/index.md) window. + In the Sales workspace, item availability data is displayed when a user adds a stock item to a sales order in the sales order window: For the selected warehouse, you can view the quantity on hand and quantity available. + In the Purchases workspace, item availability data is displayed when a user adds a stock item to a purchase order in the purchase order window: For the selected warehouse, you can view the quantity on hand, quantity available, and quantities on purchase order receipts and orders.

Related pages

Concepts

Windows

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