About Redmoon Converters

Redmoon Converters is a collection of 94 focused calculators and converters across 18 areas: cooking and baking, music production, strength training, 3D printing, home brewing, construction, photography, developer utilities and a handful of smaller niches such as beekeeping, aquariums and DIY e-liquid. Each tool does one job. You put numbers in, you get a clear answer out, and the page underneath the tool explains where that answer came from. There are no accounts, no paywalls and nothing to install.

Why we built it

Most of these conversions have a real formula behind them: the density that links cups to grams, the geometry that turns filament length into spool weight, the arithmetic that locks a delay time to a tempo. We kept re-deriving the same numbers by hand, so we built tools that get them right every time. Then we wrote up the reasoning, because a number you understand is worth more than a number you copied. That is also why the site carries a blog of 104 worked guides alongside the tools: each one takes a single conversion and works it through with real examples, the mistakes people actually make, and the point at which the simple formula stops being good enough.

How each tool is checked

The explanatory text on every tool page is written from the tool's own code, not from its name. Before a page is written we read the constants and formulas the calculator actually uses, and the write-up describes those. When a tool uses a published standard, a named formula or a rate that somebody else sets, the page carries a Where these numbers come from section that links to the source so you can check it rather than take it on trust. Tools that are pure arithmetic over your own numbers cite nothing, because there is nothing external to cite.

The whole set is periodically re-checked against what the components compute. The current check date, shown on every tool page, is August 26, 2026. When a check turns up a defect we fix the tool and the copy together. Recent examples include a board-feet calculator that undercounted by a factor of twelve, an oven fan-mode adjustment that ran in the wrong direction, and six blog posts that re-derived material an older guide already covered and were rewritten to link to it instead. We would rather publish the correction than pretend the mistake never happened.

Every tool page also states its assumptions and its limits. A sous vide table is only as safe as the thickness you measured; a cups-to-grams figure depends on how the cup was filled; a cron expression's day-of-month and day-of-week fields are combined with OR, not AND. Where an answer has a safety consequence, the page says so.

What makes the tools different

• Specific. Each tool is purpose-built for one task, with presets and units drawn from how that task is actually done, instead of a do-everything calculator with a long dropdown.
• Explained. Each tool sets out the formula it uses, the assumptions behind it and where it stops being accurate.
• Private. Calculations run entirely in your browser. The values you enter are never sent to our servers.
• Instant. Tools load as static pages and calculate as you type.
• Free. Every tool is free to use, with no sign-up and no premium tier.

Who writes this

Redmoon Converters is built, written and maintained by Paul Clark, founder of Redmoon Software, an independent software studio. The studio's main business is building apps for Atlassian Jira, which are used by more than 250,000 people through the Atlassian Marketplace. The converter sites started as a side project to scratch our own itch and grew into a small family of free utility sites: Redmoon Calculators for text, maker and worldbuilding tools, Redmoon Randomizers for random pickers and team generators, and Redmoon Business Date Calculators for working-day and deadline arithmetic. Each site covers a different set of tools; nothing is duplicated between them.

Paul writes the tool pages and the blog guides, and is the person who reads the feedback that comes in. Bylines on the blog link back to this page.

How the site is funded

The site is supported by advertising served through Google AdSense. There are no sponsored tools, no affiliate links and no paid placements: no company pays to have its product appear in a preset or a recommendation, and the numbers in the tools are not influenced by anyone who advertises here. Ads sit below the tool or the article, never between the heading and the thing you came for. Our privacy policy explains what the advertising and analytics code collects and how to opt out of personalised ads.

Corrections

If a tool gives a wrong result, a formula is off, or a guide says something that does not match your experience, we want to know. Send the tool name, the inputs you used and the answer you expected, and we will check it against the source. Confirmed errors are fixed in the tool and in the copy, and the check date on the page is updated when the set is next re-verified.

Get in touch

Spotted a bug, want a tool that does not exist yet, or have a correction to one of our formulas? Email us or head to the contact page. You can also browse all tools to see what is available today.