TakeoffMetric Construction Calculators

io.github.tresor4kv0.1.1Updated Oct 5, 2026

Construction takeoff calculators (concrete, gravel, asphalt, roofing) and sourced constants.

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Overview

AI-generated overview

Runs 15 construction takeoff calculators (concrete, gravel, asphalt, roofing, lumber, duct) and searches a sourced estimating-constants table.

What it does
A local stdio MCP server that exposes the TakeoffMetric construction calculators to an MCP client. It ships 15 calculators covering concrete slabs and cost, rebar, gravel, fill dirt, sand, topsoil, cubic yardage, asphalt, board feet, roofing and roof pitch, fencing, duct sizing and paver base, plus list_calculators and search_constants. Each calculator returns a JSON block with primary and secondary results, a takeoff list, warnings and assumptions. Inputs are optional and default to the engine's own values; results are estimates only.
When to use it
Useful when an assistant needs to turn dimensions into material quantities and order amounts for a construction or landscaping estimate, or to look up an estimating constant with its published source. It suits early takeoff and budgeting work rather than code-compliant design.
Requirements
Node.js 20 or later on the user's machine; it runs locally over stdio, typically launched with npx. No account, API key, environment variable or header is declared, and the server makes no network request. Desktop only.
Before you install
Results are estimates and should be confirmed against plans, supplier and local code before ordering or building. Prices are only what the user types in; the server holds no price data. Responses contain numbers and notes only, with no drawing or CSV export. Some constants rows return value: null with values_withheld: true because publishers do not allow republication.

Installation

In SourceWeft

  1. Open TakeoffMetric Construction Calculators in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

takeoffmetric-mcp

A Model Context Protocol server (stdio) that runs the construction calculators of TakeoffMetric (https://takeoffmetric.com/) from an MCP client. It ships 15 calculators, a tool that lists them, and a search over a table of estimating constants in which every row names its published source.

The calculators are not re-implemented here. The site's TypeScript engine is bundled unchanged into vendor/engine.mjs, and the test suite checks that each tool returns what the engine source computes.

Install

Requires Node.js 20 or later.

bash
npx -y takeoffmetric-mcp

Claude Desktop (claude_desktop_config.json):

json
{  "mcpServers": {    "takeoffmetric": {      "command": "npx",      "args": ["-y", "takeoffmetric-mcp"]    }  }}

Claude Code:

bash
claude mcp add takeoffmetric -- npx -y takeoffmetric-mcp

Tools

ToolWhat it returns
calc_concrete_slabConcrete volume, order quantity, bags, truck loads and weight for a slab, with extra sections and an optional thickened edge.
calc_concrete_costConcrete cost from your own delivered price, with short-load fee, delivery, and bags compared with ready-mix.
calc_rebarBar count each way, lap splices, stock bars, weight, intersections and supports for a slab grid or a continuous footing.
calc_gravelCubic yards, short tons and metric tonnes of gravel, stone or rock, with the compaction conversion and a truck count.
calc_fill_dirtCubic yards, tons and truck loads of fill dirt, loose or in place.
calc_sandCubic yards, short tons and a bag count for sand, by moisture condition.
calc_topsoilCubic yards, bags, weight and coverage of topsoil for a lawn, a top-dressing pass, a garden bed or a raised box.
calc_cubic_yardCubic yards, cubic feet and cubic meters over several areas, the area a volume covers, swell, bags and truck trips.
calc_asphaltShort tons and metric tonnes of hot mix by course and by area, with the spread rate.
calc_board_footBoard feet, lineal feet, pieces and cost for a lumber order of several sizes.
calc_roofingSquares, shingle bundles, underlayment rolls, ridge cap and starter from the plan footprint and the pitch.
calc_roof_pitchRise in 12, angle, grade and slope factor from any one of them, plus ridge height and common rafter length from a span.
calc_fencePosts, rails, pickets, gates and post-hole concrete for a fence line.
calc_ductRound and rectangular duct size from airflow and a friction rate or velocity limit, what a duct carries, and a reducing trunk.
calc_paver_baseCrushed stone base, bedding sand and excavation depth under a paver patio, driveway or street.

Two more tools complete the server:

  • list_calculators: tool name, title, page URL, one-line description and input keys of each calculator.
  • search_constants: rows of the constants table matched by a substring (query) and/or a category, 50 rows at most per call.

Inputs

Each calculator's input schema is generated at start-up from the engine's own input list, so keys, bounds, options and defaults are the ones of the matching form on the site.

  • Every input is optional. A key you leave out takes the engine default, as an untouched form field does.
  • system is "imperial" (default) or "metric". It sets the unit the numbers are typed in and the defaults.
  • A length is a number in the unit named in its description, or a string that carries its unit, such as "20 ft 6 in".
  • An unknown key or an out-of-range value returns isError: true with one message per field. Nothing is computed from a clamped value.

Output

A JSON text block: calculator, url, system, engine_version, revised, inputs_used, primary, secondary, takeoff, warnings, assumptions. inputs_used is the engine's normalized input (lengths in metres). assumptions lists what the result rests on, and warnings carries the cautions the page would show.

Worked example

Request (tools/call, tool calc_concrete_slab):

json
{"length":24,"width":16,"thickness":"5 in","price":165}

Response, copied from a run of this server (whitespace condensed):

json
{  "calculator": "calc_concrete_slab",  "url": "https://takeoffmetric.com/concrete/concrete-calculator/",  "system": "imperial",  "engine_version": "1.2.0",  "revised": "2026-09-19",  "inputs_used": {"system":"imperial","sections":[{"length":7.315200000000001,"width":4.8768},{"length":0,"width":0},{"length":0,"width":0}],"thickness":0.127,"wastePct":10,"bagSize":"60","pricePerCuYd":165,"thickenedEdge":false,"edgeDepth":0.30479999999999996,"edgeWidth":0.30479999999999996,"gravelDepth":0.1016,"unitWeight":150,"truckCuYd":10,"minLoadCuYd":null,"shortLoadFee":null},  "primary": {"value":6.52,"unit":"cuyd","label":"Concrete volume","precision":2},  "secondary": [    {"value":6.75,"unit":"cuyd","label":"Order quantity","precision":2},    {"value":176,"unit":"cuft","label":"Concrete volume","precision":1},    {"value":384,"unit":"sqft","label":"Slab area","precision":0},    {"value":26400,"unit":"lb","label":"Concrete weight","precision":0},    {"value":392,"unit":"bag","label":"60 lb bags","precision":0},    {"value":1,"unit":"load","label":"Truck loads","precision":0},    {"value":10,"unit":"ft","label":"Control-joint spacing","display":"10'-0″ to 15'-0″"},    {"value":1113.75,"unit":"usd","label":"Estimated concrete cost","precision":2}  ],  "takeoff": [    {"key":"readymix","item":"Ready-mix concrete","qty":5.93,"unit":"cuyd","waste":10,"order":6.75,"orderUnit":"cuyd","note":"Rounded up to the nearest 0.25 cu yd."},    …    {"key":"trucks","item":"Ready-mix truck loads","qty":6.52,"unit":"cuyd","order":1,"orderUnit":"load","note":"10 cu yd per load (your assumption)."},    {"key":"gravel","item":"Compacted base, 4″","qty":4.74,"unit":"cuyd","order":6.5,"orderUnit":"cuyd","note":"Loose volume ordered = compacted volume x 1.31 (3,570 / 2,730 lb/cu yd, FHWA Exhibit 5.1 A, gravel dry, average gradation; 1.17 uniformly graded, 1.49 well graded). For estimating purposes, ±33%: a highway embankment, not a plate-compacted base."},    {"key":"cost","item":"Concrete cost at your price","qty":6.75,"unit":"cuyd","order":1113.75,"orderUnit":"usd","note":"6.75 cu yd x $165.00 / cu yd."}  ],  "warnings": [    {"level":"caution","code":"too-many-bags","message":"392 bags is a day of mixing. Price a ready-mix delivery instead."}  ],  "assumptions": [    "Volume = length x width x thickness; 1 cubic yard = 27 cubic feet.",    "Waste allowance 10% applied to the net volume.",    "Ready-mix rounded up to 0.25 cu yd; truck capacity 10 cu yd (editable).",    …    "Unit weight 150 lb/cu ft (editable; normal-weight concrete runs about 140-155).",    "Contraction joints at 24-36 times the slab thickness, capped at 15 ft (NRMCA CIP 6).",    "Thickness, reinforcement and base depth come from your drawings or local code."  ]}

How the numbers are sourced

  • Formulas, constants and rounding rules come from the engine bundle. vendor/ENGINE_COMMIT.txt records the commit it was built from, and every response carries the calculator's engine_version and revised date.
  • Each tool computes with the same engine as its page on the site. calc_gravel, for instance, runs the engine behind https://takeoffmetric.com/earthwork/gravel-calculator/.
  • search_constants reads vendor/constants.csv (dataset 1.1.0, 148 rows). Each row gives the value, its unit, the SI value, the condition it applies to, and the publisher, title and URL of the document it was read from. 55 rows carry no value because their publishers do not allow republication: they return value: null, values_withheld: true, the publisher's domains in withheld_hosts, and the URL where the value can be read.
  • The site's methodology (tested formulas, assumptions shown on the page, sources as documents, versioned sheets) is at https://takeoffmetric.com/methodology/.

Limits

  • Results are estimates. Confirm quantities with your plans, your supplier and your local code before ordering or building.
  • This release covers 15 calculators. Calculators that apply building-code provisions, or that rely on third-party tables the site links to without reproducing them, are not part of it.
  • Responses carry numbers and notes only: no drawing and no CSV export.
  • unit fields use the engine's unit codes. Several results that are not plain counts are coded ea; read label and display for their meaning.
  • Prices are whatever you type in. The server holds no price data and makes no network request.
  • Transport is stdio only.

Development

bash
npm installnpm test

The tests run with this repository alone. npm run sync-engine and npm run make-fixtures are maintainer scripts: they rebuild vendor/ and test/fixtures.json from the site's source repository, which users of the package never need.

License

Server code: MIT. Calculation engine (vendor/engine.mjs): copyright TakeoffMetric, distributed with this package to run as part of it, not licensed for modification or separate redistribution. Both are set out in LICENSE. Constants table: CC BY 4.0 for the compilation; federal values are public domain; any other value stays under its publisher's terms. See DATA_LICENSE.md.

Source: README.md at commit 3b10dc6

Tools

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Version history

1
  1. v0.1.1LatestOct 5, 2026