---
description: The multiply compute multiplies every value of a column by a number or by another column's value.
date_published: 2026-08-13
date_modified: 2026-08-13
canonical_url: https://metricshub.org/community-connectors/develop/computes/multiply.html
---

# multiply (Compute)

On this Page

- [When To Use](#when-to-use)
- [Syntax](#syntax)
- [Properties](#properties)
- [Table Transformation Example](#table-transformation-example)
- [Recommended Pattern](#recommended-pattern)
- [Common Mistakes](#common-mistakes)
- [Community Examples](#community-examples)

## When To Use

Use `multiply` to multiply every value of one column by an operand, row by row. The operand is either a literal number or, with the `$n` syntax, the value of another column of the same row. It is the workhorse of unit conversion — kilobytes to bytes (`value: 1024`), megabytes to bytes (`value: 1048576`), ratios to percentages (`value: 100`) — and `value: -1` negates a column when you need to compute `constant - column` together with `add`. The column values must be numeric.

## Syntax

```yaml
sources:
  memoryUsage:
    type: wmi
    namespace: root\CIMv2
    query: SELECT FreePhysicalMemory,TotalVisibleMemorySize FROM Win32_OperatingSystem
    computes:
    # Convert kilobytes to bytes
    - type: multiply
      column: 1
      value: 1024
    - type: multiply
      column: 2
      value: 1024
```

## Properties

| Property | Required | Default | Description |
| --- | --- | --- | --- |
| `type` | Yes | None | `multiply`. |
| `column` | Yes | None | 1-based index of the column to update. Each value in this column is replaced by the result of the multiplication. |
| `value` | Yes | None | Multiplier. Either a literal number (e.g. `1024`, `100`, `-1`) or a `$n` reference to another column of the same row (e.g. `$3` for the 3rd column). |

## Table Transformation Example

With `column: 1` and `value: 1024`, then `column: 2` and `value: 1024`:

#### Input

| FreePhysicalMemory (kB) | TotalVisibleMemorySize (kB) |
| --- | --- |
| 4194304 | 16777216 |

#### Result

| FreePhysicalMemory (B) | TotalVisibleMemorySize (B) |
| --- | --- |
| 4294967296 | 17179869184 |

## Recommended Pattern

- Convert source units to the units expected by the metric right after collection, and record the conversion in a comment (`# Convert kilobytes to bytes`).
- Use `value: -1` followed by `add` when you need `constant - column` (e.g. endurance remaining = 100 - wear), since `subtract` only computes `column - value`.
- When the same conversion applies to several columns, chain one `multiply` per column in the same `computes` list rather than post-processing in the mapping.

## Common Mistakes

- Converting units twice: check whether the mapping already applies a conversion function (e.g. `megaHertz2Hertz`, `percent2Ratio`) before also multiplying in the compute pipeline.
- Using the wrong factor for byte conversions (`1024` for kB, `1048576` for MB — not `1000`).
- Applying `multiply` to a column that contains non-numeric text such as an empty string or a label.

## Community Examples

- [GenericUPS](https://github.com/metricshub/community-connectors/blob/main/src/main/connector/hardware/GenericUPS/GenericUPS.yaml)
- [Windows](https://github.com/metricshub/community-connectors/blob/main/src/main/connector/system/Windows/Windows.yaml)
- [WinStorageSpaces](https://github.com/metricshub/community-connectors/blob/main/src/main/connector/hardware/WinStorageSpaces/WinStorageSpaces.yaml)

From `WinStorageSpaces.yaml`, computing `100 - Wear` with a negation followed by an addition, included directly from the connector source:

```
  # Convert Wear into EnduranceRemaining (Endurance Remaining = 100 - Wear)
  # DeviceId;TotalErrors;EnduranceRemaining;WriteErrors;
- type: multiply
  column: 3
  value: -1
- type: add
  column: 3
  value: 100
```