Css length convert

css-length-convert · version 1.0.0 · Units & sizes · free, no key needed

Convert px, pt, pc, in, cm, mm, or Q using exact CSS ratios; returns a rounded decimal value.

Use when you need to: convert CSS absolute length units · pixels to inches · convert 96px to 1in.

Decide before calling

Read the versioned contract and the supported scope below. Reuse css-length-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 css-length-convert@1.0.0 for convert CSS absolute length units. 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 CSS absolute length units
• pixels to inches
• convert 96px to 1in
• points to pixels
• centimeters to CSS pixels
• convert mm to Q
• picas to points

Not supported

• convert rem or em
• convert viewport or container units
• resolve physical device pixels

Behavior

• Uses the CSS reference pixel ratios exactly: 1in = 96px = 72pt = 6pc = 2.54cm = 25.4mm = 101.6Q.
• decimals selects 0 through 18 digits after the decimal point; ties round away from zero and trailing zeroes are retained.
• Absolute-unit ratios follow CSS Values and Units Level 4 WD 2024-03-12, section 6.2; px is the CSS reference pixel, not a hardware pixel.

Input

• value (string, required): min length 1; max length 64; pattern ^-?(?:0|[1-9][0-9]*)(?:\.[0-9]+)?$
• from_unit (one of "px", "pt", "pc", "in", "cm", "mm", "Q", required)
• to_unit (one of "px", "pt", "pc", "in", "cm", "mm", "Q", required)
• decimals (integer, required): min 0; max 18

Output

• value (string, required)
• unit (one of "px", "pt", "pc", "in", "cm", "mm", "Q", required)
• standard_version (constant "CSS Values and Units Level 4 WD 2024-03-12", required)
• data_version (constant "css-absolute-length-ratios-2024-03-12", required)

Limits

• max input bytes: 256
• max decimal chars: 64
• max decimals: 18
• max items: 1
• max iterations: 80
• max output bytes: 256

Example

Request input:

{
  "value": "96",
  "from_unit": "px",
  "to_unit": "in",
  "decimals": 2
}

Response:

{
  "result": {
    "value": "1.00",
    "unit": "in",
    "standard_version": "CSS Values and Units Level 4 WD 2024-03-12",
    "data_version": "css-absolute-length-ratios-2024-03-12"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "css-length-convert",
  "version": "1.0.0",
  "input": {
    "value": "96",
    "from_unit": "px",
    "to_unit": "in",
    "decimals": 2
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/css-length-convert/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"value":"96","from_unit":"px","to_unit":"in","decimals":2}'

The machine-readable contract is at /v1/tools/css-length-convert/versions/1.0.0.

CLI

node cli.mjs run css-length-convert 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Css px to rem: Convert px to rem or em with a supplied root or parent font size; returns an exactly rounded relative length.
• Css rem to px: Convert rem or em to px using a supplied root or parent font size; returns an exactly rounded pixel length.
• Area unit convert: Convert an exact decimal area among ten SI, imperial, acre, and hectare units using pinned rational factors.
• Byte size convert: Convert a non-negative integer byte size between IEC binary units as an exact rational.
• Length convert: Convert a canonical integer length between exact SI and international customary units.
• Pressure unit convert: Convert exact decimal pressure values among seven units and return a reduced exact fraction.