# BT-149 Item Price Base Quantity

The quantity on which the item net price is based.

## Quick answer

The quantity on which the item net price is based.

> **Line items**: The goods or services on each invoice line, including quantities, prices, and VAT.

- validate
- convert

## In plain language

The quantity on which the item net price is based.

The quantity on which the item net price is based.

Describes how the invoice line price is derived, including base quantity and any price-level discount, so automated checks can recalculate line totals.

## What you usually enter here

Positive decimal quantity

Typical valid values include: 1, 100

Defined by EN 16931 for line price calculation data; required fields must satisfy the listed BR and Peppol calculation constraints.

## What goes wrong often

Avoid values like: 0, -1

Relevant rule codes: PEPPOL-EN16931-R120, PEPPOL-EN16931-R121

## Examples in context

Describes how the invoice line price is derived, including base quantity and any price-level discount, so automated checks can recalculate line totals.

Defined by EN 16931 for line price calculation data; required fields must satisfy the listed BR and Peppol calculation constraints.

## Valid Examples

- 1
- 100

## Invalid Examples

- 0
- -1

## Related Fields

Describes how the invoice line price is derived, including base quantity and any price-level discount, so automated checks can recalculate line totals.

- [BT-146 Item Net Price](/resources/xrechnung/bt-146-item-net-price)
- [BT-150 Item Price Base Quantity Unit Code](/resources/xrechnung/bt-150-item-price-base-quantity-unit-code)

## XML mapping and field facts

Open the technical reference if you need XML paths, validator rule codes, legal wording, or schema-specific mapping details.

### Field ID:
BT-149

### Data Type:
quantity

### Cardinality:
0..1

### Requirement:
Optional

### Since Version:
Optional

## XML Implementation

### UBL 2.1 Syntax
```
/Invoice/cac:InvoiceLine/cac:Price/cbc:BaseQuantity
```

## Validation Rules

### PEPPOL-EN16931-R120
PEPPOL-EN16931-R120

### PEPPOL-EN16931-R121
PEPPOL-EN16931-R121

## Why the standard cares about this field

### Business Context
Describes how the invoice line price is derived, including base quantity and any price-level discount, so automated checks can recalculate line totals.

### Legal Requirement
Defined by EN 16931 for line price calculation data; required fields must satisfy the listed BR and Peppol calculation constraints.

## Official sources and tools

- [KoSIT Validator](https://erechnungsvalidator.service-bw.de/)
- [Invoice Converter](/pdf-to-xrechnung)
- [XRechnung Standard](https://xeinkauf.de/xrechnung/)
- [Test Suite](https://github.com/itplr-kosit/xrechnung-testsuite)