# Volume unit convert

`volume-unit-convert` · version 1.0.0 · Units & sizes · free, no key needed

Convert exact decimal volumes among SI, cubic, US liquid, and imperial units with explicit half-even rounding.

**Use when you need to: convert volume units exactly · liters to US gallons · imperial gallons to liters.**

## Decide before calling

Read the [versioned contract](/v1/tools/volume-unit-convert/versions/1.0.0) and the supported scope below. Reuse `volume-unit-convert@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `volume-unit-convert@1.0.0` for convert volume units exactly. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- convert volume units exactly
- liters to US gallons
- imperial gallons to liters
- convert cubic feet to cubic meters
- US fluid ounces to milliliters
- compare US and imperial gallons
- exact cubic inch volume conversion

## Not supported

- convert mass or weight units
- convert dry-volume or cooking-cup units
- infer units from free-form text

## Behavior

- Input value is a canonical signed base-10 decimal string without exponent notation or redundant leading zeros.
- Factors are exact rational liters per unit: the international inch is exactly 25.4 mm, the US liquid gallon is 231 cubic inches, and the imperial gallon is 4.54609 liters.
- US liquid and imperial gallons, quarts, pints, and fluid ounces are distinct units and are never aliases.
- exact_fraction is reduced; value uses integer round-half-to-even at optional precision 0..50 (default 18), then removes trailing fractional zeros and negative zero.
- All validation and arithmetic are synchronous, bounded, locale-independent, offline, and deterministic.

## Input

- `value` (string, required): min length 1; max length 100; pattern `^[+-]?(?:0|[1-9][0-9]*)(?:\.[0-9]+)?$`
- `from_unit` (one of "milliliter", "liter", "cubic_centimeter", "cubic_meter", "cubic_inch", "cubic_foot", "us_fluid_ounce", "us_pint", "us_quart", "us_gallon", "imperial_fluid_ounce", "imperial_pint", "imperial_quart", "imperial_gallon", required)
- `to_unit` (one of "milliliter", "liter", "cubic_centimeter", "cubic_meter", "cubic_inch", "cubic_foot", "us_fluid_ounce", "us_pint", "us_quart", "us_gallon", "imperial_fluid_ounce", "imperial_pint", "imperial_quart", "imperial_gallon", required)
- `precision` (integer, optional): min 0; max 50

## Output

- `value` (string, required): min length 1; max length 256; pattern `^-?(?:0|[1-9][0-9]*)(?:\.[0-9]+)?$`
- `exact_fraction` (string, required): min length 3; max length 512; pattern `^-?(?:0|[1-9][0-9]*)/[1-9][0-9]*$`
- `from_unit` (one of "milliliter", "liter", "cubic_centimeter", "cubic_meter", "cubic_inch", "cubic_foot", "us_fluid_ounce", "us_pint", "us_quart", "us_gallon", "imperial_fluid_ounce", "imperial_pint", "imperial_quart", "imperial_gallon", required)
- `to_unit` (one of "milliliter", "liter", "cubic_centimeter", "cubic_meter", "cubic_inch", "cubic_foot", "us_fluid_ounce", "us_pint", "us_quart", "us_gallon", "imperial_fluid_ounce", "imperial_pint", "imperial_quart", "imperial_gallon", required)

## Limits

- max input bytes: 256
- max value chars: 100
- max precision: 50
- max output bytes: 1024

## Example

Request input:

```json
{
  "value": "1",
  "from_unit": "us_gallon",
  "to_unit": "liter"
}
```

Response:

```json
{
  "result": {
    "value": "3.785411784",
    "exact_fraction": "473176473/125000000",
    "from_unit": "us_gallon",
    "to_unit": "liter"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "volume-unit-convert",
  "version": "1.0.0",
  "input": {
    "value": "1",
    "from_unit": "us_gallon",
    "to_unit": "liter"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/volume-unit-convert/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"value":"1","from_unit":"us_gallon","to_unit":"liter"}'
```

The machine-readable contract is at [/v1/tools/volume-unit-convert/versions/1.0.0](/v1/tools/volume-unit-convert/versions/1.0.0).

### CLI

```sh
node cli.mjs run volume-unit-convert 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

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