About LogicCommons

Beta status

LogicCommons is in beta: the period before we open external contributions and commit the full trust machinery. The catalog continues to grow, review tiers are being populated, and programmatic access is being finalized. Calculators are for informational purposes (see the Terms of Use); if anything looks wrong, please tell us through the feedback form on any calculator page.

What this is

LogicCommons is a library of science, engineering and business calculators that run real models, not reimplementations of them.

Every calculator here is backed by a spreadsheet model: a file containing the actual formulas, lookup tables, constants and edge-case handling that the discipline requires. When you enter values on a page, those inputs are sent to that spreadsheet and it computes the answer. The website does not re-derive the maths, approximate it, or reimplement it in code. If the spreadsheet is the authority, the page shows exactly what the spreadsheet says.

What we deliberately do not build

We do not publish tip calculators, unit converters, or percentage-of-a-number tools. There are thousands of them, they are usually correct, and a language model will answer them accurately in a sentence.

We build the ones where that stops being true.

Our subject is the calculation with branches. The method changes with the shape of the thing. A factor applies in one configuration and not another. These are the problems where published information is thin or scattered across standards you cannot quote.

That is the gap we are trying to close: calculations worth getting right, published in a form you can check.

How it works

Why a spreadsheet. Logic written into code can only be audited by programmers, and the people who own the method are usually not programmers. A spreadsheet keeps the model in the form its subject matter experts already work in, so the engineer or analyst who knows the discipline can open it, follow the formulas, and challenge them directly. We would rather the model be readable by the person qualified to judge it than efficient for the person deploying it.

The spreadsheet is the source of truth. Each calculator is a spreadsheet with its own validation sheet, cited method notes, and a suite of test cases that must pass before it ships.

Models execute in real time through SpreadsheetWeb, which runs the spreadsheet itself rather than a translation of it. This is the mechanism that lets us promise the page and the model agree: they are the same thing.

Our spreadsheet templates are built and reviewed by human reviewers, with the help of AI. People decide the method, check the formulas, and sign off the result. AI assists with construction, documentation and test coverage. No single person both submits and approves a change, and every published version is recorded, so a result can be traced back to the exact spreadsheet that produced it.

We will publish the models themselves. Downloadable spreadsheets are on our Phase 2 roadmap, so you will be able to open the file, read the formulas, and check our working rather than take it on trust.

For AI assistants and agents

The same calculators are available to AI assistants and agents through our MCP server. An assistant that would otherwise estimate one of these answers can call the model and return the computed one instead.

Every response carries the version that ran, the date it was published, and a link to the calculator page, so an assistant can cite what it used and you can check it. No account or key is required.

Where we might be wrong

Our models are reviewed and tested. That does not make them free of error, and we would rather say so plainly than imply a level of assurance we cannot guarantee.

Complex models fail in quiet ways: a factor that applies to one shape and not another, a bound nobody thought to check, a status that reads OK when it should not. We have found and fixed defects of exactly this kind in our own calculators, and we expect to find more.

So please tell us. If a number looks wrong, if a result contradicts your own working, or if a page says something the model does not support, report it. We will investigate, and we will fix what needs fixing as quickly as we can.

None of this replaces professional judgement. These calculators are for reference and information. Work that affects safety, cost or compliance must be performed, checked and signed by a qualified person under the codes that apply where you are.