# CivilKit Calcs

> CivilKit Calcs is a free, browser-based engineering calculation sheet. It runs entirely in the browser (no server, works offline) on a Rust port of the CalcpadCE engine. A sheet is plain text: Markdown prose with `name: expression` lines that carry real units, so results come out in the right units. It also reads and writes Calcpad worksheets, and exports to HTML, PDF, Word and Excel.

Key facts for tools and assistants:

- A sheet starts with `<!--sheet-->`. A quantity line is `name: expression -> unit | note`, for example `Mstar: w * L^2 / 8 -> kN*m | design moment`.
- An input line is `L: ? 6 m` (a number box in Input mode); `L: ? 6 m [2 .. 12 step 0.5]` adds a slider.
- Units are checked: a stress times a section modulus comes out as a moment. `-> %` shows a ratio as a percentage.
- Diagrams are Mermaid fences written in the sheet; plots, Python blocks and symbolic algebra are built in.
- A slider that redraws a chart live is a Python block with `import ui` and `@ui.panel(ui.slider(...))` on a function that returns a Plotly figure: see https://civilkit.io/calcs/guide/python-panels .

The whole guide in one file: https://civilkit.io/calcs/llms-full.txt

## Guide

- [Introduction](https://civilkit.io/calcs/guide/): CivilKit Calcs is an engineering calculation sheet that runs in your browser.

## Getting started

- [Your first sheet in five minutes](https://civilkit.io/calcs/guide/getting-started/first-sheet): This walk-through builds a bending check for a simply supported beam.
- [The screen](https://civilkit.io/calcs/guide/getting-started/screen): The window has five parts.
- [Saving, opening and working offline](https://civilkit.io/calcs/guide/getting-started/saving): The File button at the top left of the ribbon opens a menu.

## Writing calculations

- [The sheet format](https://civilkit.io/calcs/guide/sheet/): A sheet is a calculation written the way you would explain it to a colleague: Markdown prose, plain name: value lines, and LaTeX where you want a typeset formula.
- [Quantities, units and notes](https://civilkit.io/calcs/guide/sheet/quantities): A quantity line defines a name.
- [Prose, LaTeX and tables](https://civilkit.io/calcs/guide/sheet/prose): Anything that is not one of the line kinds is Markdown prose.
- [Diagrams](https://civilkit.io/calcs/guide/sheet/diagrams): A diagram is written as text in a fenced block tagged mermaid, and the results draw it.
- [Folding sections and key results](https://civilkit.io/calcs/guide/sheet/sections): A long calculation has a few numbers the reader came for and a lot of working that leads to them.
- [Conditions and loops](https://civilkit.io/calcs/guide/sheet/flow): The branches are a quoted text or quantities.
- [Functions](https://civilkit.io/calcs/guide/sheet/functions): A line with an argument list defines a function.
- [Mixing in Calcpad, Show compiled and errors](https://civilkit.io/calcs/guide/sheet/passthrough): Every feature of the Calcpad language stays reachable from a sheet.
- [The Calcpad language](https://civilkit.io/calcs/guide/calcpad/): The sheet format is a front end.
- [Directives and commands](https://civilkit.io/calcs/guide/calcpad/directives): A directive starts with # and controls the flow of the worksheet.
- [Input forms with #UI](https://civilkit.io/calcs/guide/calcpad/ui-inputs): In a sheet, most inputs do not need it.
- [Units](https://civilkit.io/calcs/guide/units): Units are part of the value.
- [Vectors and matrices](https://civilkit.io/calcs/guide/vectors-matrices): In a sheet, a bracket makes a vector or a matrix.
- [Function and command reference](https://civilkit.io/calcs/guide/reference/functions): This page is generated from the editor's own snippet library (book/gen-reference.py), so it lists what the Insert tab and the ribbon offer.

## Plots and Python

- [Plots](https://civilkit.io/calcs/guide/plots): There are three ways to draw: the plot line of the sheet format, the Calcpad $Plot and $Map commands, and Python blocks, which are covered in Python blocks.
- [Python blocks](https://civilkit.io/calcs/guide/python): A sheet can hold small Python programs.
- [Interactive panels](https://civilkit.io/calcs/guide/python-panels): An interactive panel is a set of controls drawn above a chart, a table or a line of text, all made by one Python block.

## Tools

- [Templates with inputs](https://civilkit.io/calcs/guide/templates): A template is a calculation that you fill in rather than edit.
- [Symbolic maths](https://civilkit.io/calcs/guide/symbolic): The calculation engine is numeric: it gives you numbers.
- [Importing worksheets](https://civilkit.io/calcs/guide/importing): The worksheet importer converts worksheet files from a spreadsheet-like calculation format, with text, equations, plots and pictures placed freely on a page (files ending .xmcd and .mcdx), into a new Calcpad worksheet that this engine calcu
- [Importing a spreadsheet](https://civilkit.io/calcs/guide/importing-spreadsheets): Any one of.
- [Number format](https://civilkit.io/calcs/guide/number-format): Some languages write 1,5 where others write 1.5, and group digits as 1.000,5 or 1 000,5.
- [Exporting](https://civilkit.io/calcs/guide/exporting): A calculated sheet leaves the page in four ways: a PDF through the print dialog, a Word document, an Excel workbook and standalone HTML.
- [Editing](https://civilkit.io/calcs/guide/editing): There are two places to edit: the source on the left and, in the results, the page itself.
- [Embedding a calculator](https://civilkit.io/calcs/guide/embedding): An embed shows one sample sheet on another web page: its inputs as a small form and its results beside or under it.
- [Using it from an AI assistant (MCP)](https://civilkit.io/calcs/guide/mcp): An AI assistant such as Claude can run your calculations in CivilKit Calcs through the public MCP server at https://civilkit.io/mcp.

## More

- [Samples tour](https://civilkit.io/calcs/guide/samples): The Samples browser (File > Samples..., or the Resources tab) lists 151 worksheets, with groups, a search box and a preview.
- [Troubleshooting and FAQ](https://civilkit.io/calcs/guide/troubleshooting): An error appears in the results where the line would, as a red paragraph, in the Errors dialog, and as an underline in the editor.

## Appendices

- [Keyboard shortcuts](https://civilkit.io/calcs/guide/appendix/shortcuts): On a Mac use Cmd where this page says Ctrl.
- [Deviations from CalcpadCE](https://civilkit.io/calcs/guide/appendix/deviations): CivilKit Calcs reproduces CalcpadCE's output exactly unless a behaviour is listed in the project's DEVIATIONS.md.
- [Credits and licences](https://civilkit.io/calcs/guide/appendix/credits): CivilKit Calcs is built on CalcpadCE, the MIT-licensed continuation of Calcpad by Nedelcho Ganchovski (Proektsoft) and contributors.

## MCP

CivilKit Calcs has a public, read-only, stateless MCP server (Streamable HTTP, no sign-in) at https://civilkit.io/mcp . It runs sheets and Calcpad worksheets in the same engine as the app and returns the values with their units. Add it to Claude Code with `claude mcp add --transport http civilkit-calcs https://civilkit.io/mcp`. Tools:

- `calcs_evaluate_sheet`: Evaluate a CivilKit Calcs sheet
- `calcs_evaluate_calcpad`: Evaluate a Calcpad worksheet
- `calcs_convert_units`: Convert units
- `calcs_check_hand_calc`: Check a hand calculation
- `calcs_search_functions`: Search functions, units and commands
- `calcs_function_help`: Function documentation
- `calcs_search_docs`: Search the user guide
- `calcs_get_guide_page`: Read a guide chapter
- `calcs_list_samples`: List the sample sheets
- `calcs_get_sample`: Get a sample sheet
- `calcs_sheet_syntax`: Sheet syntax reference

More: [Using CivilKit Calcs from an AI assistant](https://civilkit.io/calcs/guide/mcp)

## Task pages

All of them, grouped by purpose: [Calculators and guides](https://civilkit.io/calcs/learn/)

- [Beam deflection formula 5wL^4/384EI, derived](https://civilkit.io/calcs/learn/beam-deflection-formula-derivation/): Derive the midspan deflection of a simply supported beam under a uniform load step by step with symbolic integration, then check it against a plotted curve.
- [Bending moment and shear force diagrams, plotted](https://civilkit.io/calcs/learn/bending-moment-shear-force-diagram/): Plot bending moment and shear force along a simply supported beam from a moment function, worked out at sixths of the span in a loop, with real units.
- [Open Calcpad .cpd files in your browser, offline](https://civilkit.io/calcs/learn/calcpad-online/): Open and run Calcpad .cpd worksheets in your browser, offline, on an open source Rust engine. Edit, plot, import and export to Word, Excel or PDF.
- [Cantilever beam calculator: tip load and deflection](https://civilkit.io/calcs/learn/cantilever-beam-calculator/): Free cantilever calculator with units: moment, shear, bending stress, tip deflection and rotation for a point load at the free end, with a moment diagram.
- [Column buckling calculator: slenderness and Euler load](https://civilkit.io/calcs/learn/column-buckling-calculator/): Slenderness and buckling of a solid rectangular column: end conditions, the Euler or parabolic critical stress and the allowed load, as a form you can edit.
- [Concrete strength gain calculator, 1 to 28 days](https://civilkit.io/calcs/learn/concrete-strength-gain-calculator/): Strength of concrete at ages from 1 to 28 days from a common strength gain formula, listed on a timeline and plotted. Edit the 28-day strength.
- [Free engineering calculation software in the browser](https://civilkit.io/calcs/learn/engineering-calculation-software-free/): A free browser tool for engineering calculations with units: templates for beams, walls, footings, pipes and pumps, plots, and Word, Excel and PDF export.
- [Engineering calculations with units, SI and US](https://civilkit.io/calcs/learn/engineering-calculations-with-units/): Write calculations where every quantity carries a unit: SI and US customary units, prefixes, unit errors that catch mistakes, and your own units.
- [Excel alternative for engineering calculations](https://civilkit.io/calcs/learn/excel-alternative-for-engineering-calculations/): Write engineering calculations with units and readable formulas instead of cell references, see the workings, and export to Word, PDF and Excel.
- [Export engineering calculations to Word, Excel and PDF](https://civilkit.io/calcs/learn/export-calculations-to-word-excel-pdf/): Turn a calculation into a Word report with real equations, an Excel workbook with native charts, or a PDF, from the browser. What each format keeps.
- [Gable frame thrust: pinned vs rigid ridge](https://civilkit.io/calcs/learn/gable-frame-thrust-calculator/): Horizontal thrust of a symmetric pitched roof frame for a pinned ridge and a rigid ridge, and why the common shortcut overstates it.
- [Free Mathcad alternative that runs in your browser](https://civilkit.io/calcs/learn/mathcad-alternative/): A free, open source engineering calculation sheet for the browser: real units, plots, Word and Excel export, offline use, and a Mathcad worksheet importer.
- [Open .xmcd and .mcdx files without Mathcad, free](https://civilkit.io/calcs/learn/mathcad-worksheet-converter/): Open Mathcad .xmcd and .mcdx worksheets without Mathcad: they convert to a live calculation sheet in your browser, and nothing is uploaded.
- [Pad footing bearing pressure calculator](https://civilkit.io/calcs/learn/pad-footing-bearing-pressure-calculator/): Free pad footing calculator: bearing pressure under a column load and moment, eccentricity, uplift and the check against an allowable soil pressure.
- [Pipe flow calculator: Darcy-Weisbach head loss](https://civilkit.io/calcs/learn/pipe-flow-darcy-weisbach-calculator/): Free pipe friction loss calculator: velocity, Reynolds number, friction factor, Darcy-Weisbach head loss, pump head and power for water in a full pipe.
- [Principal stress calculator for 2D and 3D stress](https://civilkit.io/calcs/learn/principal-stress-calculator/): Principal stresses and directions of a plane or 3D stress tensor from eigenvalues and eigenvectors, checked against Mohr's circle, with units.
- [Pump operating point calculator: pump vs system curve](https://civilkit.io/calcs/learn/pump-operating-point-calculator/): Free calculator for the operating point of a pump on a pipeline: where the pump curve meets the system curve, with a table of heads and both curves plotted.
- [Retaining wall stability calculator](https://civilkit.io/calcs/learn/retaining-wall-stability-calculator/): Free retaining wall calculator: active earth thrust, overturning and sliding safety factors and base pressure for a cantilever wall, with units.
- [Principal axes of an unsymmetric section, calculated](https://civilkit.io/calcs/learn/section-principal-axes-calculator/): Strong and weak axes of an unsymmetric cross-section from the second moments of area by eigenvalues, checked against the closed-form result.
- [Shear frame natural frequencies and mode shapes](https://civilkit.io/calcs/learn/shear-frame-natural-frequencies/): Natural frequencies and mode shapes of a two storey shear frame from the generalised eigenvalue problem K phi = w^2 M phi, worked with units.
- [Simply supported beam calculator with units](https://civilkit.io/calcs/learn/simply-supported-beam-calculator/): Free beam calculator: moment, shear, bending stress and deflection of a simply supported I-beam under a uniform load, with a moment diagram. Opens as a form.

## Optional

- [App](https://civilkit.io/calcs/): open the calculator
- [Product page](https://civilkit.io/calc/): what CivilKit Calcs is and does
- [What's new](https://civilkit.io/calcs/whats-new/): release notes with short clips
- [Embed a calculator](https://civilkit.io/calcs/embed/): put a live sheet on another web page with one iframe (free, no tracking)
- [Source code and issues](https://github.com/mageaustralia/civilkit-calcs)