# Pressure unit convert

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

Convert exact decimal pressure values among seven units and return a reduced exact fraction.

**Use when you need to: convert pressure units exactly · convert pascals to psi · convert kilopascals to bar.**

## Decide before calling

Read the [versioned contract](/v1/tools/pressure-unit-convert/versions/1.0.0) and the supported scope below. Reuse `pressure-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 `pressure-unit-convert@1.0.0` for convert pressure 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 pressure units exactly
- convert pascals to psi
- convert kilopascals to bar
- convert atmospheres to torr
- convert torr to millimetres of mercury
- exact pressure conversion
- pressure unit fraction conversion

## Not supported

- convert temperature or mass units
- look up measured atmospheric pressure

## Behavior

- Accepts only canonical ASCII decimal strings and the seven declared unit names.
- Uses declared exact rational pascal factors; returns a reduced fraction and a finite canonical decimal when one exists, otherwise numerator/denominator.
- No rounding occurs; negative zero canonicalizes to zero.

## Input

- `value` (string, required): min length 1; max length 100; pattern `^-?(?:0|[1-9][0-9]*)(?:\.[0-9]+)?$`
- `from_unit` (one of "pascal", "kilopascal", "bar", "atmosphere", "torr", "psi", "millimetre_of_mercury", required)
- `to_unit` (one of "pascal", "kilopascal", "bar", "atmosphere", "torr", "psi", "millimetre_of_mercury", required)

## Output

- `value` (string, required): min length 1
- `numerator` (string, required): pattern `^-?(?:0|[1-9][0-9]*)$`
- `denominator` (string, required): pattern `^[1-9][0-9]*$`
- `from_unit` (one of "pascal", "kilopascal", "bar", "atmosphere", "torr", "psi", "millimetre_of_mercury", required)
- `to_unit` (one of "pascal", "kilopascal", "bar", "atmosphere", "torr", "psi", "millimetre_of_mercury", required)

## Limits

- max input bytes: 256
- max value bytes: 100
- max fraction digits: 98
- max output bytes: 512

## Example

Request input:

```json
{
  "value": "1",
  "from_unit": "atmosphere",
  "to_unit": "pascal"
}
```

Response:

```json
{
  "result": {
    "value": "101325",
    "numerator": "101325",
    "denominator": "1",
    "from_unit": "atmosphere",
    "to_unit": "pascal"
  }
}
```

## How to call it

### MCP

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

```json
{
  "id": "pressure-unit-convert",
  "version": "1.0.0",
  "input": {
    "value": "1",
    "from_unit": "atmosphere",
    "to_unit": "pascal"
  }
}
```

### HTTP (no key)

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

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

### CLI

```sh
node cli.mjs run pressure-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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