About CALCULA
CALCULA is a scientific calculation notebook: you write your calculations
one under another, as on a sheet of paper, and the cells talk to each other. A cell defining
m = 2.5 kg makes that symbol usable throughout the rest of the document; correcting its
value recomputes everything that depends on it. That is the fundamental difference from a
calculator: you do not start a calculation over, you correct a datum.
What the notebook can do, one sentence each: carry units and uncertainties through the calculation; work out on its own the chain of formulas leading from a known quantity to the one you want; read a data file and fit a model to it; solve a differential equation and plot its phase portrait; run real Python in a cell; add a profession's operations through a subject pack; and export to LaTeX, a Jupyter notebook, Word, PDF, or a share link holding the entire notebook. The guides cover each of these, with an example to replay.
Two principles held throughout. Every result says how it was obtained: under each calculation, the “Steps” panel gives the breakdown as you would write it by hand, and the “How?” panel the exact expression the engine received, the algorithm and the duration. And nothing of the teaching side is hidden: a glossary of 2,500 formulas — 2,272 of them directly computable — stays readable and insertable while you compute, with an explanatory tooltip for each formula and each keyboard key.
How it works, technically
The scientific engine (SymPy, NumPy, SciPy) runs entirely in your browser through Pyodide — no calculation is sent to a server. See the Privacy page for the details.
Support Calcula
Calcula is free, without advertising and without any tracking — no analytics, no cookies. If the tool is useful to you, you can support its development with a donation of any amount: you choose how much, and it is a one-off payment, with no subscription and no later charge.
The payment happens on a page hosted by Stripe. No banking data passes through calcula.ch, and no Stripe script is loaded into this site: the button is a plain link, and nothing is called until you click it. The site does not know who donated — it has no account, no identifier and no way of recognising you (see the privacy policy).
Who is behind this site
CALCULA is published by Alexandre Gertsch, in a personal capacity, under the name “Impulse Orbit” (L'Ancienne Route 77A, 1218 Le Grand-Saconnex, Geneva, Switzerland). See the legal notice for the complete information.
The same author also publishes impulsestation.ch and impulsestation.org (free online tools: file conversion, units, QR codes…) and CapBudget.ch (free financial-education guides).