Free engineering calculation software in your browser
CivilKit Calcs is a calculation sheet for engineers that runs in a browser tab. You write quantities with units and formulas as readable text; the page works them out, typesets them, plots them if you ask, and prints or exports a report. It is free and open source, it works offline once loaded, and no calculation is sent to a server.
What it is for
It suits the calculations an engineer does many times a year and wants to read back later: a member check, a bearing pressure, a head loss, a quick plot of a function. Each calculation is a document with its inputs, steps and checks in order, so the person who reviews it can follow it.
# Beam moment
L: 6 m | span
w: 12 kN/m | design load
M: w * L^2 / 8 -> kN*m | maximum momentThat is a complete sheet. It reports a maximum moment of 54 kN·m. The units were multiplied and converted by the engine.
Ready-made calculators
These templates are sheets with inputs. Choose Open this template on any page and the sheet opens in the app as a form. All of them are generic textbook calculations, not design-code checks, and each page says what it assumes.
- Simply supported beam calculator: moment, shear, bending stress and deflection of an I-beam, with a moment diagram.
- Retaining wall stability calculator: earth thrust, overturning, sliding and base pressure for a cantilever wall.
- Pad footing bearing pressure calculator: eccentricity, largest and smallest soil pressure, uplift.
- Pipe flow calculator, Darcy-Weisbach: velocity, Reynolds number, friction factor, head loss and pump power.
- Pump operating point calculator: where a pump curve meets a pipeline curve, with both plotted.
More calculators, from a cantilever and column buckling to principal stresses and concrete strength gain, are listed in Calculators and guides. The app also has more than a hundred sample worksheets from the CalcpadCE project.
If you are coming from another tool
- Mathcad alternative, and how to open Mathcad files without Mathcad.
- Calcpad worksheets in the browser, if you already use the Calcpad language.
- Excel alternative for calculations that need their workings shown.
What is in the box
- Real unit algebra, vectors and matrices, a large function library.
- Plots from one line of a sheet, and Python blocks for Plotly-style and matplotlib-style charts.
- Input forms from a
?in front of a value: boxes, drop-downs, radio buttons and checkboxes. - A symbolic dialog for exact algebra, with documented limits.
- Export to Word (with real equations), Excel (with workings and native charts), PDF through the print dialog, and HTML.
- A worksheet importer for Mathcad files.
- A user guide with short how-to videos.
What it is not
It is not a finite element package, a structural design suite or a drawing tool. It does not carry design standards: the checks you write, and the ones in the templates, are as correct as the formulas in them. The project is early, so check any result you will rely on against a method you trust.
It is built on CalcpadCE, the MIT licensed Calcpad by Nedelcho Ganchovski (Proektsoft) and contributors, with a Rust engine compiled to WebAssembly.
Questions
Is it free for commercial use?
Yes. It is MIT licensed and free to use, with no account.
What do I need to run it?
A current browser. You can install it as an app and use it offline after the first visit.
Is my work stored on a server?
No. Calculations run in your browser and files are kept in its local storage or saved to your computer.
Does it include design codes?
No. The templates are generic textbook calculations. You can write any formulas into a sheet, but the checks are yours.
Where do I start?
Open a template from this page, then read the guide chapter "Your first sheet in five minutes".