Mass add

mass-add · version 1.0.0 · Units & sizes · free, no key needed

Add mixed-unit canonical integer mass amounts and express the sum in a target unit as a reduced rational.

Use when you need to: mass add · add mass quantities · sum masses in mixed units.

Supported

• mass add
• add mass quantities
• sum masses in mixed units

Not supported

• mass multiply
• average mass
• density from mass and volume
• troy or stone units
• floating-point mass

Behavior

• terms is an array of 1 to 32 objects, each with a canonical integer string value and a mass unit.
• Units are exactly ng, ug, mg, g, kg, t, oz, and lb; t is the metric tonne, lb is avoirdupois, oz is 1/16 lb.
• Each term is converted to nanograms as BigInt and the nanogram amounts are summed.
• The sum is converted to the to unit as the reduced rational sum_ng / to_ng.
• Negative term values are allowed; -0 canonicalizes to 0.
• Unknown fields, unknown units, empty or overlong terms arrays, and reduced results over 1000 digits are rejected.

Input

• terms (array of object, required): min items 1; max items 32
• to (one of "ng", "ug", "mg", "g", "kg", "t", "oz", "lb", required)

Output

• numerator (string, required): pattern ^(0|-?[1-9][0-9]*)$
• denominator (string, required): pattern ^[1-9][0-9]*$

Limits

• max digits: 1000
• max terms: 32

Example

Request input:

{
  "terms": [
    {
      "value": "1",
      "unit": "kg"
    },
    {
      "value": "500",
      "unit": "g"
    }
  ],
  "to": "g"
}

Response:

{
  "result": {
    "numerator": "1500",
    "denominator": "1"
  }
}

How to call it

MCP

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

{
  "id": "mass-add",
  "version": "1.0.0",
  "input": {
    "terms": [
      {
        "value": "1",
        "unit": "kg"
      },
      {
        "value": "500",
        "unit": "g"
      }
    ],
    "to": "g"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/mass-add/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"terms":[{"value":"1","unit":"kg"},{"value":"500","unit":"g"}],"to":"g"}'

The machine-readable contract is at /v1/tools/mass-add/versions/1.0.0.

CLI

node cli.mjs run mass-add 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Byte size add: Add non-negative integer byte-size terms in mixed IEC units and return the exact sum in a chosen unit.
• Length add: Add integer length terms in mixed units and return the exact sum in a chosen unit.
• Mass compare: Compare two mixed-unit canonical integer mass amounts using exact nanogram BigInt values.
• Mass convert: Convert a canonical integer mass amount between exact nanogram-based units as a reduced rational.
• 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.