How we calculate

The math is kept separate from the interface

Every calculator's math lives in its own dedicated module — one per calculator, more than three hundred in total — written as pure functions: the same inputs always produce the same outputs, with no hidden state and no network access.

Because the math layer is strictly separated from the interface, the exact same code runs when a page is pre-rendered on the server and when you interact with it in your browser. The answer cannot differ between the two.

Decimal arithmetic at 30 significant digits

Ordinary floating-point arithmetic famously answers 0.1 + 0.2 with 0.30000000000000004. To avoid this whole class of error, calcu.lol's math runs on decimal arithmetic (the decimal.js library) configured to 30 significant digits — including trigonometry, logarithms, and roots, not just addition and multiplication.

Displayed results are rounded for readability, but the underlying computation keeps full precision, so intermediate steps do not accumulate drift.

Your inputs are never sent anywhere to be computed

Calculations run entirely on your device. The numbers you type are not transmitted to a server for processing — there is no calculation backend at all. This is the same guarantee described in the privacy policy.

Every result is a link

The full state of a calculator — every input you've entered — is serialized into the page's address. Copy the link and anyone who opens it sees the same inputs and the same result. This also makes results reproducible: a link is a complete, self-contained record of a calculation.

How correctness is checked

Accuracy is enforced by an automated test suite that runs before every deployment:

• Unit tests exercise the calculator math modules against known values and edge cases; most modules have a dedicated test suite.
• Registry invariant tests enforce that every published calculator has a math module, an interface component, and translations in all 8 languages — a calculator cannot ship half-wired.
• Route-health tests exercise every calculator page in every language (312 calculators × 8 locales) to verify each one loads and declares correct metadata.

Where data comes from

Almost every calculator is self-contained mathematics and needs no external data. The one exception worth naming: the currency converter uses a static snapshot of exchange rates, not a live feed — and it says so on the page, with the date the rates were captured.

The limits, honestly

High-precision arithmetic guarantees the formula is computed accurately; it does not guarantee the formula fits your situation. A TDEE estimate, a BMI category, or a loan projection is a simplified model of reality.

Results are provided for information and education only. They are not medical, financial, tax, legal, or engineering advice — the terms of service carry the formal disclaimer. For decisions that matter, verify independently and consult a qualified professional.

Found an error?

If a calculator produces a wrong result, the operator wants to know. Report it through the GitHub profile github.com/dvddvd300 — precise inputs (or simply the shareable link, which contains them) make it fixable.