Editorial policy
This page describes how content on Numvella is written and maintained. It is a statement of the standards each page is held to, so you can judge whether a page meets them.
Who writes this content
Numvella is operated as an independent project. Content is published under the Numvella name rather than under individual bylines. We do not claim professional credentials in finance, medicine, law, or accounting, and nothing here is written or reviewed by a licensed professional in those fields. Where a calculation touches a regulated or personal-risk area, the page says so and points you to a qualified professional.
What every calculator page must explain
A calculator that only prints a number is not much use if you cannot check it. Each calculator page is expected to cover:
- What the tool does and what the inputs mean, stated up front.
- The formula, written out, with every variable defined.
- At least one worked example showing inputs, the arithmetic, and the result.
- The assumptions built into the calculation, and where it stops being appropriate.
- How rounding is handled, and what happens with invalid or unusual inputs.
- Links to genuinely related calculators, not a generic block of links.
Pages are written for the person doing the calculation. We do not add text to reach a word count, repeat keywords to influence ranking, or publish near-identical pages that differ only in the numbers they mention.
How sources are chosen
Most of the arithmetic here is standard mathematics — the definition of a percentage, the mean of a list, the relationship between distance, time, and pace. Definitions like these do not need a citation, and adding one would be decoration rather than evidence.
Citations belong where a calculation depends on an external fact that can change or be disputed: a published equation attributed to specific researchers, a statutory rate, a classification threshold set by an organisation, or an industry convention. In those cases the page names the source, and we prefer the body that defines the standard over a secondary write-up of it. Where a figure varies by country or changes over time, the page says so rather than presenting one value as universal.
Correctness is not the same as suitability
A calculator can implement a formula perfectly and still give you a number that is wrong for your situation, because the formula itself carries assumptions. We treat these as two separate questions and try to be explicit about both: whether the arithmetic is right, and whether this is the right arithmetic for you. See Methodology for how the first is checked.
When pages are reviewed again
A page should be revisited when something material changes — the formula or its implementation, a source it relies on, the behaviour of the tool, or a reported error that turns out to be real. Routine edits like fixing a typo do not count as a review.
We do not put a “last reviewed” date on a page unless a review actually happened, and we do not refresh dates to make content look current. A date that does not correspond to real work is worse than no date at all.
Corrections
If something here is wrong, we want to fix it. Our corrections policy explains how to report an issue and what happens after you do.