About

This site publishes small calculators for decisions that are usually made on gut feeling, and it tries to be explicit about what each one can and cannot tell you.

What it is

Three tools so far: the annual cost of upgrading a laptop, the cost of waiting for the next model, and a readiness check for a macOS upgrade. Each one takes a handful of inputs, applies a published formula, and states the result in plain numbers rather than a score.

There are no accounts, no email capture, and no calculator sends your inputs anywhere. Everything runs in your browser.

Who runs it

One person, independently. No company, no investors, no editorial team, and no sponsored placements. That is worth saying plainly because most calculator sites are lead-generation in disguise: they exist to move you toward a purchase, and the maths is tuned accordingly.

How the numbers are checked

Every formula is published in full on the tool's "how it works" page, so you can reproduce the output by hand. Each calculator ships with automated tests: fixed scenarios with expected results, plus edge cases including zero, negative, and very large inputs. If a formula changes and the tests are not updated, the site does not deploy.

Where a page states a fact about a product or an operating system, it is checked against the vendor's own documentation at the time of writing, and the date is stated on the page.

The correction policy

If something here is wrong, it gets fixed and the fix is visible. Pages that had a model correction say so in the page itself rather than quietly changing the numbers; the upgrade calculator carries a section explaining what the first version got wrong and why.

Report errors to the address on the contact page. Corrections take priority over new content.

How it is funded

Advertising and affiliate links, when they exist, pay for the hosting. Advertising does not influence which tools exist, what the formulas are, or what the pages say. A tool that concludes "do not buy" stays published, because a calculator that only ever recommends buying is an advertisement.

As of the date below the site carries no advertising at all; the placeholder slots are empty.

What it will not do

It will not publish "best of" lists, buying guides, or rankings. It will not add a tool it cannot state the formula for in a paragraph. And it will not pretend a number is precise when the input it depends on is a guess.

Contact

Email is on the contact page. Corrections, questions about a formula, and reports of a page that produces a nonsense result are all welcome and all get answered.