First — the rule and its limits

Verification starts with a question: what exactly does the calculator solve? For percentages, it's a mathematical operation; for salary, a calculation under Estonian rules for the chosen period; for clothing sizes, matching measurements against a published table. Each tool has its own input data and limitations.

Calculations tied to legislation need official sources and the dates the rules apply. The date we opened a document does not become the date it entered into force. If a period or exception is not supported, it cannot be quietly replaced with the nearest available option.

We check the formula, then the interface

The calculation logic is separated from translation and design. So the same input data and rules must produce the same numbers in all four languages. The way a number is written may differ, but not the result itself.

Checks include examples with a known answer in advance and edge cases. What matters is the rounding of monetary amounts, zero values, unsupported conditions and input errors. We then check whether it's clear to a person what to enter and what the resulting figure means.

ChatGPT, Claude and local language models in LM Studio help write code, break down formulas and look for inaccuracies. Their answers also need to be checked. A successful test is useful, but on its own doesn't prove that the tool covers every life situation.

A change in the source — a reason to look closer

The project has a mechanism prepared for checking changes in official sources and future revisions of regulations. A detected change doesn't automatically mean the formula has become wrong: it's necessary to understand whether it affects a specific calculation and from what date.

At the time this article was written, the legal monitor's regular schedule is not yet enabled, and analysis with Codex is triggered manually. That's why we don't promise that the calculators will update themselves by a specific date. A new revision goes through review, and a person makes the decision to publish.

Check the selected period, sources and explanations next to the result. If you notice a discrepancy, let us know which calculator you used and under what conditions. To report an error, you don't need to send personal documents or someone else's personal data.